Ash Ketchum is now 10 years old and is able to start on a new journey as a Pokémon trainer. The night before Ash has to go meet Prof. Oak he has a dream and breaks his alarm. The next day he oversleeps, which causes him to miss his chance at getting one of the three Kanto starter Pokémon: Charmander, Bulbasaur or Squirtle. However, Professor Oak has one last Pokémon at his lab, a Pikachu. At first Pikachu does not get along with Ash, but in the first episode Ash saves Pikachu from a crew of evil Spearows and they become best friends, developing a special bond. On the way Ash meets Misty, the Cerulean City Gym Leader who loves water Pokémon and wants to join him until he pays her for her bike which was accidentally destroyed by Pikachu, and Brock, the Pewter City Gym Leader who wants to join Ash on his journey so he can become the greatest Pokémon breeder. Ash catches and makes friends with many Pokémon, which sets him up for a great adventure. However, through his journey he has to deal with the Team Rocket trio of Jessie, James, and Meowth, and his childhood rival, Gary Oak, Professor Oak's grandson, who also is a Pokémon Trainer, who got a Pokémon before Ash, and always seems two steps ahead of him. After obtaining all 8 Kanto Gym Badges needed to compete in the Pokémon League at Indigo Plateau, Ash is finally ready to compete in the renowned Pokémon League! Misty and Brock support him through everything he does. Misty hopes for money for the bike Pikachu wrecked.
Ash Ketchum is finally 10 years old, old enough to become a Pokémon Trainer. He wakes up late on the day he is supposed to receive his first Pokémon at Professor Oak's lab, however, and arrives to discover all the Pokémon are gone. Ash has no choice but to take a naughty Pikachu. Pikachu won't listen or go inside its Poké Ball, so Ash must drag it along with a rope. After many failed attempts at capturing some Pokémon, Ash throws a rock and hits a Spearow. The Spearow gets angry and the entire flock starts chasing Ash and Pikachu. They run away from the Spearow, but when they cannot go any farther, Ash uses his body to shield Pikachu from the attacking Pokémon. Pikachu realizes how much Ash cares for him and uses a powerful electric attack to drive the Spearow away.
Finally arriving in Viridian City, Ash is cornered by Officer Jenny who asks why he is carrying Pikachu instead of having it in a Pokéball. After explaining, Jenny takes Ash to the Pokémon Center where Nurse Joy begins treatment on the injured Pikachu. Before Pikachu's treatment finishes, however, Ash is interrupted by Misty, the girl who Ash took the bike from, who vows to stick with Ash until he pays her back for destroying her bike. The Pokémon Center is then attacked by Jessie, James, and their talking Meowth, members of the villainous Team Rocket, seeking to steal all of the infirm Pokémon. Ash's Pikachu and the Pokémon Center's many Pikachu manage to defeat Team Rocket by shocking them, sending them "blasting off" into the sky.
Ash, Pikachu, and Misty have entered the Viridian Forest. Ash captures his first Pokémon, a Caterpie, and later, a Pidgeotto. Misty, however, is scared of bugs and screams every time Caterpie comes near her. Meanwhile, Team Rocket is following them, ready for a fresh attempt at capturing Pikachu. Ash is successful in driving off Team Rocket once more, and Ash's Caterpie evolves into Metapod.
While wandering through Viridian Forest, a Samurai challenges Ash to a battle, and it turns out to be Metapod vs. Metapod. After a short time, a swarm of Beedrill attacks, and Ash's Metapod is taken by them. Ash is able to rescue his Metapod and it evolves once more into Butterfree.
Ash and Misty finally reach Pewter City and meet Flint, a mysterious man who sells rocks. Ash is ready to challenge the Pewter City Gym Leader, Brock, for his first Badge, but loses the battle. Flint takes Ash and Pikachu to Brock's home and Ash learns that Brock cares for his many younger brothers and sisters since their dad left them. He then brings Pikachu and Ash to a watermill to make Pikachu stronger. Ash battles Brock again, this time coming closer to winning. A fire breaks out in the gym, however, and the sprinklers go off, weakening Onix. Ash wants to defeat Onix but is held back by the thought of Brock's siblings (when he opens his eyes he finds he was literally held back by them). Ash leaves the Gym but Brock catches up to him and gives Ash the Boulder Badge. Flint turns out to be Brock's father and takes over the Gym and the responsibility of his children for Brock when he decides to join Ash on his journey.
Ash, Misty, Brock, and Pikachu arrive at Mt. Moon to find Team Rocket interfering with the local wildlife in hopes of finding the rare Moon Stone. With the help of Seymour the Scientist, the gang saves the Moon Stone and the Clefairies that guard it. Also, Brock catches a Zubat.
In his quest to collect Gym Badges, Ash heads for Cerulean City, intending to confront the Cerulean Gym Leader. For some reason, Misty expresses a desire to avoid Cerulean City and disappears along the way. Upon entering the gym, Ash and Pikachu are entranced by a synchronized swimming show being performed by three beautiful sisters, unsure if he has really found another Gym. The three reveal that they are the Gym Leaders but have since converted the Gym into an aquarium and water show, and offer to just give Ash the badge, but Misty appears once more, revealing that she is also one of the Gym Leaders and will battle Ash in lieu of her three older sisters. However, Team Rocket disrupts the battle in an attempt to steal all of the Gym's Pokémon, and Misty's sisters decide to award Ash the Cascade Badge for helping save everyone.
After receiving his second badge, Ash sets off triumphantly for Vermilion City. Along the way, they hear of a trainer named A.J. - a fierce Pokémon trainer who has never lost a match. Full of self-confidence from his own record of ten victories in a row, Ash heads directly for the gym to find his new opponent. When they arrive, a huge bulletin is in front of the gym with a neon sign declaring "98 Consecutive Victories", which appeals to Ash's over-confidence. A.J. is on the brink of achieving his goal of 100 straight victories, after which he will embark on a journey to gather badges, and Ash discovers A.J.'s odd training style.
Our three heroes have lost their way in the depths of a dense wooden forest, shrouded in thick, white mist. Momentarily giving up, they decide to break for a brief rest. As Ash wanders deeper into the wood, searching for firewood, he happens across a young boy being bullied by five classmates gathered around him. Eavesdropping on their conversation, Ash learns that the boys are attending a preparatory school for Pokémon trainers. Graduates from the school are automatically qualified to participate in the Pokémon League without travelling around and collecting any badges. Ash, Misty, and Brock head to the school and do not agree with some of their ideas of training, something their "leader" does not take well.
Ash and friends are still on their way to Vermilion City and still lost. They stop by a pond for a break when they see an Oddish taking a drink. Ash and Misty try to catch it but they are stopped by a mysterious Bulbasaur who rescues the Oddish. They continue on their journey and keep getting caught in traps, until the Bulbasaur's owner, Melanie, finds them, saves them and brings them back to her cabin. It turns out that she helps injured, sick, and abandoned Pokémon, and they decide to help. Meanwhile, Team Rocket decides to steal all the Pokémon, while Brock wonders if he should stay with Melanie. In the end, Melanie gives Bulbasaur to Ash, but not until Bulbasaur challenges Ash and Pikachu to a battle.
While on the road to Vermilion City, Ash, Misty, Brock, and Pikachu come across a Charmander sitting on a rock. Ash tries to catch it, but it turns out it has a trainer and cannot be captured, so they head to the Pokémon Center. At the center, a hotshot trainer named Damian is bragging about how he left his Charmander behind, promising to come back for it when he means to abandon it for being weak in his eyes. After hearing this, they head back out to get the poor Pokémon as a rainstorm threatens its very life. After a battle with Team Rocket, where Damian witnesses Charmander defeating them, he tries to get Charmander to come back to him, but the Pokémon's loyalty now belongs to Ash. Ash captures Charmander, gaining a new friend and Pokémon.
Ash, Misty, Brock, and Pikachu become the victims of pranks played by a gang of rogue Squirtle known as the Squirtle Squad. They end up falling down a hole, and are even eventually captured by them. It turns out that they are working together with Team Rocket. When Pikachu is severely injured, the lead Squirtle lets Ash out to get medicine from town, but must return soon or his friends will be trapped by the Squirtle Squad forever. In the end, the Squirtle Squad saves the town from a fire started by Team Rocket and the lead Squirtle joins Ash on his further adventures.
When a Krabby that Ash catches disappears, he goes to a nearby lighthouse to see if it reached Professor Oak's lab. The keeper of the lighthouse is Bill, a Pokémon Watcher who is searching for a mysterious Pokémon that sometimes appears by his lighthouse. Just as this mysterious Pokémon answers Bill's call and approaches the lighthouse, Team Rocket appears and tries to capture it. Injured, the Pokémon loses its trust of Bill and vanishes forever, though Bill intends to keep an eye out in case it ever appears again.
Ash finally arrives in Vermilion City and is ready to prove that he can defeat its Gym Leader Lt. Surge. However, Lt. Surge and his powerful Raichu easily defeat Ash, and he discovers that many trainers fail to defeat Lt. Surge. After contemplating evolving Pikachu into Raichu as well, Ash decides to use Pikachu's speed to his advantage in his next battle, defeating Lt. Surge and winning the Thunder Badge.
Ash "wins" a ticket to take a trip on a luxury cruise ship, the St. Anne. Ash enjoys the journey, even tradin Butterfree for a Raticate, but feels guilty afterwards and asks for Butterfree back. However, the whole cruise is a scheme devised by Team Rocket, who plans to steal the Pokémon of all the trainers onboard. During the confusion, James purchases a Magikarp from a devious salesman, under the impression it will make him rich, unaware of Magikarp's true nature. After Team Rocket's plans fail, the St. Anne is hit by a powerful storm. Ash loses his Butterfree's Poké Ball in the confusion and goes to get it, just as James tries to retrieve Magikarp's Poké Ball, and both groups are knocked unconscious while the rest of the passengers escape safely.
Ash, Misty, Brock, and Pikachu wake up aboard the St. Anne, discovering it has capsized and sunk. Elsewhere, Jessie, James, and Meowth wake up as well, and in an attempt to escape only flood the area that they are in. When Ash and his friends find Team Rocket, the group decides to put their differences aside to escape safely, after an attempted battle nearly causes the ship to sink farther. After traversing the ship, they find a weak part of the hull to escape from, using Misty and Ash's water Pokémon to escape, while Team Rocket uses James' Magikarp, unaware that it cannot swim. After making it to the surface on some debris, the group discovers Team Rocket, once more, and after a day stranded, decide to eat Magikarp, only discovering that it has no meat on it. In anger, James kicks Magikarp off the raft and it evolves into Gyarados. It calls a group of other Gyarados toa attack the group, and everyone is stranded once more.
Everyone finds themselves stranded on a strange island, with the humans and Pokémon separated. Both discover that the island appears to be inhabited by gigantic Pokémon. After being hit by a Dragon Rage attack from James' newly evolved Gyarados while at sea, the humans are separated from their Pokémon on an island containing many giant Pokémon. Pikachu, Bulbasaur, Charmander, Squirtle, Meowth, Ekans, and Koffing try to make their way back to their trainers, while they escape the giant Pokémon, unaware that they have all landed on an island owned by Team Rocket to house a theme park dedicated to giant robotic Pokémon.
Ash and his friends have finally arrived in Porta Vista, a beachside tourist town. After destroying an old man's ship, they must help in the old man's business. To attempt to pay the man back faster, Misty enters a beauty contest, only to discover she is competing against Jessie and James (with fake breasts).
Stuck in Porta Vista because they missed the boat, Ash and friends sit around waiting for the next boat and witness a great explosion. They later discover that it is a group of Tentacool that is attacking the city since construction is destroying their reef. Ash and his friends manage to appease the giant Tentacruel and continue on their journey, with Misty catching a Horsea that was bein harassed by the Tentacool.
The boat that Ash and his friends are on docks at a small town celebrating Obon. Brock and James both fall for a beautiful girl standing by the sea who disappears. Ash, Misty, and Team Rocket learn that she is the ghost of a maiden who waited for her lover to return from a war and eventually turned into stone. While trying to protect Brock and James with some stickers bought from an old woman, the maiden reveals herself as the old woman, who in turn reveals herself to be Gastly, a ghost Pokémon. Ash tries to fight Gastly to release James and Brock from its spell but fails, until the sun rises and Gastly is forced to disappear. It is revealed that the ghost of the maiden actually exists and is a friend of Gastly, and is still waiting for the one she loves to return.
As the group continues on their way, they notice a flock of Butterfree out over the ocean. Brock informs Ash that it is the mating season for all of the Butterfree. Ash decides to release his Butterfree so that it can mate. However, Team Rocket has plans to steal them all. Ash's Butterfree bravely frees all the Butterfree and in the end Ash releases it.
Ash and his friends finally arrive in Saffron City, but before Ash can enter the Saffron Gym he is warned by a strange man not to go in. Ash enters anyway to discover a strange training facility for people with psychic powers. Ash challenges Sabrina, the heartless Gym Leader and her Abra who evolves into Kadabra, and loses. They are transported into a toy box set and forced to play with a dangerous little girl, the group is rescued by the strange man who gives Ash a tip: he may be able to beat Sabrina with a Ghost Pokémon from Lavender Town.
Team Rocket encounters the Ghost Pokémon in a haunted tower while setting a trap for Ash and his friends, and end up getting frightened away. Ash and Pikachu enter alone since his friends are afraid to go in. Inside, he and Pikachu are the victims of pranks by a Gastly, Haunter, and Gengar looking for playmates. After being crushed under a falling chandelier, Haunter turns Ash and Pikachu into ghosts where they have some fun, though Ash asks them to send him back after seeing Misty and Brock cry over his lifeless body. Ash and Pikachu are brought back to life and Haunter decides to follow Ash as his new Pokémon.
Ash and his friends go back to Saffron City ready to try again for the Marsh Badge in the Gym. Ash asks Haunter for help to defeat Sabrina but Haunter disappears during the match. Brock and Misty get turned into dolls, and Ash is rescued just in time by the mysterious man. The man reveals that Sabrina has two personalities — one of the cold and unfeeling trainer, the other of the repressed little girl, who also turned her mother into a doll. The only way to defeat Sabrina is to make her smile again. During the next match, Haunter suddenly appears in front of Sabrina while Kadabra and Pikachu are battling. Sabrina and her Kadabra become unable to battle after being sent into peals of laughter by Haunter, giving Ash the victory.
As Ash is on his way towards Celadon City, he encounters a Mankey. The Mankey starts chasing him and steals Ash's hat. Ash tries to get it back and fails. Team Rocket arrives to get Pikachu and when Mankey walks by, James kicks it away and in its anger, evolves into Primeape. After remembering the words Professor Oak said, Ash captures it.
When Ash reaches the Celadon Gym, he is kicked out because he is a boy. He soon discovers that it is only for girls, so with the help of Team Rocket, Ash sneaks into the Gym disguised as a girl. In the Gym, his disguise is ruined by Misty, Brock, and Pikachu, but the Gym Leader Erika grants him a battle. During the battle, Team Rocket interrupts and sets the Gym on fire. After rescuing Erika's Gloom, Ash is presented with the Rainbow Badge.
Ash and his friends arrive at a town where many of the town's children are disappearing. They discover that a Hypno, a hypnotic Pokémon is responsible. Adults in the town have come to help their insomnia by being put to sleep by Hypno. However there is a side effect, making the children think they are different Pokémon and run away and put real Pokémon to sleep. Ash stops Team Rocket from stealing Hypno and uses the Pokémon Drowzee to bring all the children and Pokémon back to normal. A useless Psyduck follows Misty around, and after she drops a Poké Ball, Psyduck activates it and captures itself, much to Misty's dismay.
Team Rocket plans a scheme to steal many Pokémon by opening a grooming shop. Ash and his friends meet Susie, a famous Pokémon breeder. In the end, Brock gains a Vulpix when Susie tells him to look after it as she goes off to learn more about Pokémon breeding.
After meeting a girl whose father is more concerned about training his fighting Pokémon Hitmonchan at the gym instead of his daughter, Ash enters a Fighting Pokémon-only tournament with his Primeape. Team Rocket also enters and resorts to cheating, stealing another man's Hitmonlee, in order to win. After learning how much his daughter means to him and winning, the man promises to train Primeape to make him stronger, so Ash gives it away and promises to return.
The group arrives in Gringy City where everything is dark and gloomy. A Magnemite follows Pikachu everywhere ever since it caught a peculiar illness, but it is the Grimers and Muk that are causing trouble in a local Power Plant. Ash captures Muk and Pikachu is cured of his cold.
Ash finds himself among a group of Pokémon Trainers hired to protect a construction site from the interfering ground Pokémon Diglett. The construction is shut down after it is revealed that the Digletts and Dugtrio are trying to protect their home. Jessie's Ekans and James' Koffing evolve into Arbok and Weezing respectively.
The group finds a strange-looking ninja-style mansion. They explore it and encounter various traps. Soon, they discover that this is the Fuchsia Gym and Ash battles Koga, the Gym Leader, for the Soul Badge. When Team Rocket disrupts their battle, Misty discovers how powerful her Psyduck really is.
The group arrive at the Laramy Ranch where a family of ranchers, with their daughter Lara and her Ponyta, prepares for an annual Pokémon race. Ash takes over as Ponyta's rider when Lara gets hurt due to Team Rocket's interference. Then, Team Rocket helps a rival competitor to win the race by setting up traps for other participants. As the race continues, however, Ponyta evolves into a Rapidash and wins the race.
Ash and his friends reach the Safari Zone, unaware that the part they have entered is a protected preserve when an Officer Jenny disguised as Chansey nearly arrests them for poaching. They come across a wild boy named Tommy that leads a herd of Kangaskhan and eventually find Tommy's parents, who were searching for him since he was only three. Unfortunately, Tommy thinks that the Kangaskhan are his family. After battling Team Rocket, Tommy's parents also become part of the Kangaskhan family.
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Ash and his friends get challenged by Team Rocket in seeing who can capture the most Pokémon within the Safari Zone, with Ash catching a whole herd of Tauros. As soon as Ash and his friends head out Pokémon hunting, Team Rocket manages to get the drop on the game warden (Mr. Kaiza) and forces him into giving up the location on where Dratini is (the Dragon Valley). In the end, Ash, his friends, Team Rocket, and Kaiza end up seeing the legendary Dratini and Dragonair, with our heroes saving the day.
Continuing their journey, the group came across a bridge which could be used as a shortcut to the next town. They soon discover that the bridge is too long to walk and they would need bicycles to cross. They go to the Pokémon Center where Nurse Joy asks them to take some medicine to a sick Pokémon across the bridge. On their way, a bicycle gang appears to cause trouble and Team Rocket is helping them. When Ash and his friends decide to cross the bridge during a storm, the bicyclists realize that they are acting selflessly, and help them.
During a storm, Ash and his friends arrive at a mysterious Mansion. While there, Ash meets Duplica, a girl who is an expert at impersonation, and she happens to own Ditto, a Pokémon that can transform into any Pokémon. However, Ditto cannot seem to figure out how to change its face, a fact that stopped Duplica's variety show. As they all try to help Ditto perfect its transformation, Team Rocket tries to steal the Ditto so it can transform into a Dratini which they can give to the boss.
-NOT AIRED IN THE US-
Ash and his friends arrive at Pokémon Center where the Poké Ball transfer machine has been causing problems, as the transferred Pokémon never end up at the other side. Ash and his friends decide to accompany Porygon, a computerized Pokémon, used by Professor Akihabara to investigate the problem, only to discover Team Rocket and another Porygon are to blame.
The group come into a forest where it is quiet and peaceful. They notice a large group of Pikachu that Ash's Pikachu tries to make friends with. After saving a young Pikachu from drowning and rescuing the herd from Team Rocket, Ash's Pikachu is welcomed among the other Pikachu as one of their own. Saddened by this sudden distance, Ash tries to leave Pikachu behind (to Misty and Brock's shock and dismay), thinking that in the long run, it is going to be better off with its own kind. As they attempt to leave the forest with Ash still standing his ground on leaving Pikachu, the three friends are surprised when Pikachu returns to them, flanked by the other wild Pikachu including the younger Pikachu it risked its life to save earlier. The episode ends with Ash and Pikachu having an emotional reunion and hugging one another while the rest of the wild Pikachu cheer for the two of them as Brock and Misty look on.
While traveling through the woods, the group encounters an Eevee that was apparently abandoned near a tree. They take it to its address in Stone Town and find it belongs to a little boy named Mikey. His three brothers are pressuring him into evolving his Eevee into one of three forms — Jolteon, Vaporeon, or Flareon — at an Evolution Party, where everyone uses Evolution Stones to evolve their Pokémon. However, the Evolution Party is disrupted by Team Rocket, and Mikey manages to use Eevee on its own to show his brothers that he does not need to evolve his beloved Eevee.
Ash and his friends arrive at a town which is having problems with their water source. It seems that a Snorlax is blocking the water path. Team Rocket plans to capture the Snorlax, but Ash and his friends find help from an unexpected source.
Upon entering Dark City, Ash and his friends discover that Pokémon Trainers aren't liked due to two rival Gyms who involve Ash and the gang as well as Team Rocket in their feuds to become the city's legitimate Pokémon Gym.
When at a carnival, Ash and his friends meet a magician who is really losing his touch and fails in his own magic show. In his effort to get better, he decides to hypnotize Ash and uses his Pokémon Exeggcute to capture loads of Exeggutor. But the Exeggutor end up hypnotizing themselves and Team Rocket and almost destroy the entire carnival. Luckily, they are saved by Charmander, who then evolves into a disobedient Charmeleon.
Having run out of medicine, Ash and his friends go to a local shop to get some Potions. However, they don't have much due to the owner's Paras being weak. Ash and his friends decide to help out the owner by training her Paras, hoping that it can evolve into Parasect.
Entering Neon Town, a bustling Metropolis where everyone is tired and rude, Ash and his friends find a Jigglypuff who is too shy to sing its hypnotic song. Realizing they can kill two birds with one stone, Misty tries to teach the Jigglypuff to sing while Team Rocket attempts to record the song so they can use it against Ash. Everyone falls asleep, including Ash and his friends and Team Rocket, and a miffed Jigglypuff uses the marker hidden in her microphone to draw on everyone's sleeping faces. From this point on, Jigglypuff follows Ash around trying to sing her song to a crowd that will not fall asleep in almost every episode.
Arriving at a canyon to find an old fashioned fossil hunt, Ash, Gary and the gang decide to join in. But Team Rocket arrives and intends to blow the canyon up. In doing so, Ash, Pikachu, and Team Rocket fall into a pit which is full of awakened ancient Pokémon. Their only hope may rest in Ash's disobedient Charmeleon, which evolves into a powerful, yet still disobedient Charizard to defeat a raging Aerodactyl. In the end, the ancient Pokémon are sealed away once more (along with a terrified Team Rocket) and Officer Jenny dismisses the entire event as a side effect caused by Jigglypuff's singing. Ash, however, finds a rare Pokémon egg in the chaos and keeps it.
After Pikachu gets an apple stuck in its throat, Ash and his friends rush it to a hospital. After being treated, they hear of a traffic accident(caused by Team Rocket) that has left many Pokémon injured so Ash and the gang are recruited to help treat the Pokémon.
After finding a missing person sign featuring James, Ash and his friends decide to find James and inform him of his parents' death. However James' parents turn out to be alive, and their death was only a decoy to get him to return home to the rich Jessebell, a girl James was arranged to marry from whaen he was a ittle chid. James has left because Jessebell is terrifying, so everyone tries to save James from this fate, including James' old pet Growlithe Growlie.
When Misty's Pokéballs are stolen by a Farfetch'd, Ash and the gang investigate to try to find the thief and get all the stolen things back.
When the egg Ash found hatches into a brand new Pokémon, Togepi, everyone wants to own it. They decide to have a small Pokémon Tournament. Ash, who found it, claims he should be the one to keep it. In the end, Ash wins the tournament, but since Misty was the first person Togepi saw when he hatched, he thinks she is his mother and stays with her.