Ash Catches a Pokémon (Japanese: ポケモンゲットだぜ! I Caught A Pokémon!) is the third episode of the Pokémon anime series, except in the United States, where it was broadcast fourth due to Battle Aboard the St. Anne being aired as the first episode. The episode was first broadcast in Japan on April 15, 1997 and in the United States on September 10, 1998.
Ash has caught a Caterpie. However, Misty's bug-o-phobia makes her uneasy, as she does not want the worm with her. Though Ash captures a Pidgeotto, Team Rocket appear once more to get the Pokémon for themselves. How will Ash defeat them, as Pidgeotto is exhausted and Caterpie is not very well trained for the battles yet?
The episode begins with Ash throwing a Poké Ball at Caterpie, following on directly from the last episode. Ash captures it and celebrates the capture of his first Pokémon, stating that this is the beginning of his journey to becoming a Pokémon master. Ash attempts to show Misty his Poké Ball with Caterpie inside, although Misty is less than pleased due to her fear of bug Pokémon. After showing the Poké Ball to Pikachu, Ash releases Caterpie. Caterpie goes to climb on to Ash's shoulder but notices a scared Misty hiding behind a tree and runs over. Caterpie attempts to befriend Misty, but her fear leads to her hurting Caterpie's feelings, calling it 'disgusting'.
Misty decides to stick with Pikachu and then tells Ash that she hates bug Pokémon, carrots and peppers. Ash then angrily tells Misty that he doesn't like the way she is hurting Caterpie's feelings. Caterpie then climbs on to Ash's shoulder and the two, along with Pikachu, leave Misty on her own in the forest. As Ash is walking away, Pikachu notices that Misty is following them. Ash and Misty argue once again, with Misty stating that she's following him to get the new bike he owes her. The two camp next to the same tree stump but continue arguing. After Ash and Misty fall asleep, Caterpie and Pikachu begin a conversation after looking up at the moon and the night sky. Caterpie tells Pikachu about its desire to evolve into a Butterfree, with one seen flying in the sky.
Caterpie, quickly becomes depressed after looking at Misty, but decides to sleep next to her in an attempt to become friends. Misty, after waking up, screams and wakes Ash and Pikachu up. Misty shouts at Caterpie to get inside its Poké Ball and, depressed, it does so. Ash and Pikachu attempt to make Caterpie feel better, as a Pidgeotto flies down and begins pecking the ground. Ash throws a Poké Ball but Pidgeotto bats it away with its wing, resulting in Misty telling Ash that he needs to battle Pidgeotto to weaken it before attempting to capture a Pokémon.
Ash then sends Caterpie to battle against Pidgeotto, with Misty and Pikachu being shocked and concerned for Caterpie's safety, due to bug Pokémon's weakness against flying types. Pidgeotto begins to attack Caterpie and gets the upper hand by using tackle attack from out of the sky. Caterpie rolls up against a tree and Ash calls it back, resulting in Pidgeotto flying into the tree. Ash then sends Pikachu out and uses Thundershock, which hits Pidgeotto. Ash throws a Poké Ball and captures Pidgeotto. A confident Ash attempts to impress Misty by saying that that is how a Pokémon master works, but Misty angrily tells him that Pokémon trainers need to know strategy, which includes not sending a worm Pokémon against a bird Pokémon, as birds eat worms.
Jessie, James and Meowth of Team Rocket then show up and perform their song/motto. Jessie and James then begin to tell Ash and Misty their plans, resulting in Meowth using its scratch attack to stop them. Meowth then begins to tell Ash and Misty their plans, so Jessie and James attack him to shut his mouth. Jessie and James then bring out Ekans and Koffing, with Koffing taking Pikachu out of action by using sludge attack. Ash then sends out Pidgeotto in a two against one attack. Koffing attempts to use sludge again but Pidgeotto dodges it and then a tackle attack by Ekans. Pidgeotto attempts to use quick attack against Ekans, who goes underground to avoid the attack. Koffing attempts to use SmokeScreen, which Pidgeotto avoids by flapping its wings, and then dodges sludge attack and Ekans' tackle attack from underground. Pidgeotto flies away but is followed by Koffing and Ekans. Pidgeotto attempts to use Gust attack to get rid of Koffing, who dodges the attack and uses tackle attack, quickly followed by Ekans.
Ash recalls Pidgeotto and then attempts to fight James on his own, but James stops him and pushes away. Pikachu states its intention to battle but Misty tells it that it can not battle due to Koffing's sludge covering its eyes. Ash then sends out a tired Caterpie. Ekans and Koffing then attack, with Misty again showing concern for Caterpie. Ash, however, has Caterpie use String Shot to cover Koffing completely and Ekans head with string, before using tackle on Koffing, which flies into Ekans. Caterpie then uses its string shot on Meowth. Team Rocket, with no Pokémon able to battle, run off but threaten to return. Ash celebrates his first ever Pokémon match victory. Misty congratulates Caterpie for its victory, saying that it is stronger than it looks.
Ash says that Misty should congratulate Caterpie but, as she is about to touch Caterpie, it begins to use string shot continuously. Caterpie then evolves into Metapod, with Ash using his Pokédex to learn more information about Metapod. Pikachu then remembers Caterpie's desire to become a Butterfree and Ash introduces himself to Metapod, before holding it next to Misty, as they were about to become friends. A Beedrill flies past and Misty tells Ash that she'll do anything to get out of Viridian Forest and away from the bug Pokémon. Ash, however, says that he is going to stay to capture more Pokémon and runs off, with Misty deciding to follow him.
- "Bugs get me all bugged out! Even when they're in a Poké Ball. Just keep it away!" — Misty expressing her hatred towards bugs
- "I guess it takes a worm to love a worm." — Misty
- "Very funny." — Ash
- "It's so gross. Ash, put that slimy thing back in the Poké Ball! Bugs are one of the three most disgusting things in the world!" — Misty
- "Aside from you, what are the other disgusting things?" — Ash
- "Very funny. Carrots, peppers and bugs. Everybody has something they don't like and I don't like bugs!" — Misty
- "I am the greatest." — Ash
- "You're the worst! You have no idea what you're doing. It'll be a long time before you're a Pokémon master, like a million years." — Misty
- "(sigh) I'm trying to-" — Ash
- "You should try to learn something about Pokémon first. With Pokémon you've got to use strategy. Pidgeotto is a bird. Caterpie is a worm. Birds eat worms Mr. Pokémon Master!" — Misty
- "Well, if you just try hard enough, things will work out. Won't they?" — Ash
- "No, Ash, I'm afraid things won't just work out if you try hard enough. The Pokémon trainers judgment is more important than anything else, and unfortunately for you the trainer has to have a brain." — Misty
- "Beaten by a Caterpie." — James
- "That really bugs me." — Jessie
- The 'Who's That Pokémon' of this episode is Caterpie.
- The episode's name is read by Misty for the first time, so as to avoid Ash referring to himself in the third person.
- The episode features the first Pokémon evolution of the anime series, when Caterpie evolves into Metapod.
- Pidgeotto can be seen eating a worm, one of the few instances of non-Pokémon creatures being seen.
Misty again slaps Ash during this episode, like she did during Pokémon - I Choose You!, but this scene was again cut after its initial airing, but it was heard.