Ash first saw Corphish in the episode, "Which Wurmple is Which?", while fishing. However, Corphish ran away. In the episode, "Gone Corphishin' ", a strange figure was moving underground. Brock had a plan to reveal the figure and the plan worked. Ash realized that he caught a same Corphish before on the fishing rod. Ash wanted to capture it again so he used Pikachu. Pikachu was no match for Corphish despite the type advantage. Treecko was sent out instead. Using the method that Ash and his Pokémon practiced, Treecko was able to overcome Corphish's strength and thus, Ash was able to catch it.
Corphish was a surprisingly strong fighter, helping Ash through many battles. For starters, Ash used it in the rematch Gym battle against Brawly and replaces Taillow. It fights against his Machop, already weakened by Treecko, and wins, but loses against Hariyama. Then, it was used against Lavaridge Town's Gym Leader, Flannery, and wins against her Magcargo, then fights against her Slugma after Treecko got burned in the leg due to an indirect impact by a Flamethrower, but was put to sleep by Yawn, although Pikachu defeated Slugma. Corphish is then used against Flannery's Torkoal, who easily defeated both Pikachu and Treecko, but it's still asleep. When it wakes up, it uses Crabhammer beneath Torkoal's shell, making it dizzy and finishes it off with Bubble Beam, earning Ash the win and the Heat Badge. It also contributes in Ash's Gym Battle against Juan. In the first round, it fights alongside Pikachu against Sealeo and Seaking, who defeated Snorunt, and defeats Sealeo with Crabhammer, while Pikachu defeats Seaking. In the second round, a 3-on-3 battle, Corphish was used against Juan's Luvdisc, who previously defeated Grovyle easily. Despite Luvdisc's Swift Swim ability, Corphish manages to defeat it with Crabhammer before being defeated by Whiscash. In battle, Corphish displayed remarkable stamina as in the Hoenn League, against Dominick, it fights alongside Torkoal against a Tropius and a powerful Swalot, and after a draw between Torkoal and Tropius, Corphish endures several super-effective Shock Waves, a Shadow Ball, two Body Slams and a Sludge Bomb from Swalot, but still managed to defeat it by firing a Bubble Beam in the mouth. It was also used as Ash's fourth Pokémon in his Full Battle against Katie and fights against her Golduck, who defeated Torkoal. Corphish gets confused by Golduck's Confusion, but despite that, it manages to attack normally, throwing Golduck in the air and winning the round with Bubble Beam, but is still confused, so it gets recalled. Corphish is then sent out again to fight against Katie's final and strongest Pokémon, Walrein, who defeated Swellow, but it's too tired and loses, just like Swellow. Corphish is Ash's first Pokémon he uses in his battle against Morrison, and it defeats both his Girafarig and his Growlithe, but when Ash tells him to snap out of it, he sends out his Swampert, and the round ends in a tie. (In the manga, Corphish defeats Swampert too, but loses against Steelix.) In the quarter-finals against Tyson, Corphish was used against his Hariyama, who defeated Torkoal, but gets defeated as well.
Corphish's resilience was displayed again when it battled Tucker's Swampert and Arcanine alongside Ash's Swellow, defeating Arcanine, while Swellow defeated Swampert. Corphish was also used in both of Ash's battles with Salon Maiden Anabel. In the first battle, it fights against her Alakazam and lost. In the rematch, it was used again against Alakazam and won before being defeated by her Metagross.
It appeared again in Sinnoh region when Ash asked Professor Oak to sent his Pokémon. Though it didn't take part in any of the battles.
At Prof. Oak's Lab, Corphish and Totodile were seen underwater when Misty and Lana dived into the lake to find Popplio.
- Katsuyuki Konishi (Japanese)
- Maddie Blaustein (English 4Kids dubbed)
- Bill Rogers (English PUSA dubbed)
- Corphish is Ash's only Hoenn Pokémon capable of evolving, yet to never doing so, because of this it tended to get jealous when Ash chose an evolved Pokémon over it.
- When Corphish uses "Bubble Beam" the colors of the bubbles vary per episode.
- Corphish is also Ash's only Hoenn Pokémon that hasn't learned a new move.
At Oak's Lab
At Kukui's house
At Cerise Laboratory