Ash caught Corphish in the episode Gone Corphishin'. Ash and his friends were camping on a beach, and Corphish was attacking them from underneath the sand. Eventually, its identity was revealed and Ash battled it and caught it using his Treecko.
In the next episode, when Corphish met the gang's other Pokémon, it struggled to make friends, smacking the others to greet them and eating their food. In the same episode, Corphish fell ill after eating some seaweed and rope and was carried to the Dewford Town Pokémon Center by its new Trainer Ash. The next morning, it had recovered and was able to stop Team Rocket's plan. Corphish had its first Gym battle in Just One of the Geysers against Brawly, where it was chosen to battle his Machop, Corphish won the battle but still fell to Hariyama.
In Going, Going, Yawn!, when discussing Ash's strategy for his next Gym Battle, Ash showed his friends that he would use Corphish since the Gym was a Fire-type Gym. When the battle started, Ash used Corphish as his first Pokémon in his Lavaridge Gym, it went up against Flannery's Magcargo. Corphish was able to hit with Bubble Beam and then it countered Magcargo's Flamethrower with Harden. Brock told Ash to beware that although damage was small, it would add up, but Ash was overconfident since Flannery was a new Gym Leader annoying Flannery. Corphish used Bubble Beam but Magcargo used Double Team to avoid damage and only ended up hitting the Double Team clones. But Corphish was able to destroy them by attacking from above as well as hitting Magcargo. Later Corphish used Vice Grip but Flannery had Magcargo use Reflect, pushing Corphish back and cutting the damage by half. Magcargo then counterattacked with Sandstorm, damaging Corphish. It used Bubble Beam while Magcargo used Sandstorm again with Sandstorm overpowering Bubble Beam. However Corphish jumped over Magcargo and used Crabhammer downwards, pushing back the Sandstorm and hitting Magcargo knocking it out. Ash recalled Corphish when Flannery sent out her Slugma. However after Treecko was recalled, Corphish was sent out to battle Slugma. Slugma used Smog but Corphish was able to blow it away with a spinning Crabhammer. It then used Vice Grip but Slugma used Yawn putting Corphish to Sleep. Ash wasn't able to wake Corphish up and it was hit by another Flamethrower. Ash recalled Corphish. Ash later sent it out to battle Flannery's Torkoal, however it was still asleep. It was hit by Overheat, which still didn't wake up Corphish, however Overheat didn't do much damage, as Overheat decreases in power each time its used. Torkoal used Flamethrower hitting Corphish, but woke up. Vice Grip was blocked by Iron Defense and was hit by Sludge Bomb. Ash had Corphish withstand the attack and used Crabhammer, which was once again blocked by Iron Defense. Ash had Corphish used Crabhammer on Iron Defense again, but attacked it on the side, causing it to spin. This made Torkoal dizzy and forced it to come out of its shell. This allowed Corphish to finish off Torkoal with Bubble Beam, earning Ash the Heat Badge.
In Go Go Ludicolo!, Corphish was sent out when Ash was picking which Pokémon to use for his Petalburg Gym Battle, Corphish immediately got angry and jealous of Ash's newly evolved Grovyle, after Corphish failed to get oranges off a tree after using its attacks too hard, breaking the oranges, as well as failing to break Team Rocket's net with its pincers, both of which Grovyle did easily with its Leaf Blade, earning it praise and making Corphish more jealous and angry. Later Corphish barged in Grovyle's way to volunteer to battle against Poncho and his Ludicolo. However Corphish struggled as its Crabhammer and Bubble Beam attacks were dodged by Ludicolo's dancing skills, Double Team or they were blocked by Protect, Corphish was hit by Ludicolo's Focus Punch, after having more of its attacks dodged or blocked, it was defeated by Hyper Beam. May mentioned that Ash and Corphish weren't in sync. Corphish was upset about losing and later ran off. Ash later learned that Corphish was jealous of Grovyle. Corphish caught up with Poncho and got angry at him demanding another battle, later Corphish rescued Poncho and Ludicolo from Team Rocket and single handily defeating Seviper and Cacnea, impressing Poncho with him mentioning that him winning might have just been luck.
In It's Still Rocket Roll to Me!, Corphish saved Max and one of the Mossdeep Gym Leaders, Tate, when they were captured on board in a space shuttle by Team Rocket.
In Once in a Mawile, it fell in love with a Mawile, however the feeling was not mutual as the Mawile was in love with Brock's Lombre. It teamed up with the also heartbroken Brock to sing and dance to "Brock's Paradise" in order to keep an audience entertained.
In The Great Eight Fate! Ash chose Corphish to replace his Snorunt in the Double Battle in the first round of the Sootopolis Gym battle, it went up against Juan's Sealeo and Seaking along with Pikachu. Corphish used Bubble Beam, which Sealeo and Seaking dodged by diving underwater, Seaking then used Horn Attack on Corphish from behind, although Corphish grabbed Seaking's horn with its claws, Seaking used Horn Drill to spin Corphish around, crashing it into the water. When Pikachu used Iron Tail on Seaking while Sealeo used Aurora Beam on Pikachu, Iron Tail knocked out Seaking while Aurora Beam missed. Pikachu was seen riding on Corphish like a surfboard. While they rode towards Sealeo, it used Ice Ball, which was getting stronger with each attack, Corphish blocked the first two with Harden and Vice Grip while Pikachu destroyed the third one with Iron Tail, the fourth one then hit them both. Sealeo launched a fifth Ice Ball at them both, which was very large and powerful, but Pikachu was able todestroy it with a powerful Thunder while Corphish launched a Crabhammer after Sealeo was distracted with the falling ice shards, knocking Sealeo out. This ended the first round of the Sootopolis Gym battle in Ash's favour. Both were then recalled. In the next episode, Corphish was used in the second round of Ash's Sootopolis Gym battle, it went up against Juan's Luvdisc, Corphish used Bubble Beam, but using its incredible speed, Luvdisc dodged and used Water Gun which hit Corphish. Luvdisc used Sweet Kiss, but Corphish dodges and used Bubble Beam, which Luvdisc dodged by diving underwater. However, Corphish used Crabhammer at the surface of the water, forcing Luvdisc out the water and dealing damage, Corphish used Vice Grip but due to the splash creating rain like conditions, it activated Luvdisc's ability Swift Swim, allowing it to move two times as normal, allowing Luvdisc to dodge. Luvdisc used Water Gun which Corphish dodged and Ash had it use Bubble Beam on the mist, removing the rain like conditions and thus stopping Luvdisc's Swift Swim from working, this allowed Corphish to hit Luvdisc with Crabhammer, knocking it out. Corphish went up against Juan's Whiscash, Corphish used Bubble Beam, which Whiscash countered with Surf, blocking the attack, it then used the momentum from the Surf to launch its Rock Smash attack, crushing Corphish and knocking it out.
In the Ever Grande Conference, it was used in several battles. It first teamed up with Torkoal in From Brags to Riches to battle Dominick, after Torkoal fainted, Corphish was on its own to defeat Swalot, which it did by using Bubble Beam in Swalot's mouth.
In A Judgment Brawl, Ash used Corphish as his fourth Pokémon in his Full Battle against Katie in the Victory Tournament, it went up against her Golduck on the water field. Golduck used Fury Swipes, while Corphish used Crabhammer and they both collided. Golduck used Hydro Pump, which Corphish dodged and used Crabhammer, however Golduck used Confusion, trapping Corphish in the air. After being slammed on a platform, Corphish became confused and couldn't hear Ash's command for Harden and fell into the water, however it suddenly came from behind Golduck and used Crabhammer while still confused. Golduck then launched Fury Swipes which Corphish caught and used its claws to shake Golduck's hand. Corphish then launched Golduck into the air and finished it off with Bubble Beam. Corphish went up against Katie's Venomoth, Corphish was still confused and launched a Bubble Beam, which was dodged, Venomoth used Supersonic but did nothing as Corphish was already confused. Ash then recalled Corphish. Corphish was later sent out to battle Katie's last Pokémon, her Walrein. Corphish looked weak but was free from its confusion. Walrein used Body Slam and Corphish used Bubble Beam, but Bubble Beam was unable to stop Walrein and it was knocked out by the Body Slam. Ash later used Corphish as his first Pokémon in his Full Battle against Morrison in the Victory Tournament, it went up against his Girafarig. Corphish used Vice Grip and Girafarig countered with Light Screen, but that was useless in this scenario as Light Screen protected against special attacks, and Vice Grip was a physical move, breaking the Light Screen and dealing damage. Girafarig used Tackle but Corphish dodged by sliding on the ice field, causing Girafarig to crash into an ice pillar. Corphish used Vice Grip and while Girafarig jumped and dodged, Corphish used its pincer on an ice shard to turn around and hit Girafarig, it countered with Iron Tail, but Corphish ducked and defeated the Long Neck Pokémon with Crabhammer. Due to his indecision and not wanting to fight Ash, he struggled to pick a second Pokémon and was about to be disqualified.
In the next episode, Ash got Morrison to continue the battle, and he reluctantly picked Growlithe. Corphish used Bubble Beam, and Morrison had Growlithe dodge with Agility, Ash had Corphish used Bubble Beam, and Morrison countered with Agility again. At this point Ash's friends realized that Morrison was unwilling to attack and Growlithe crashed into an ice pillar. Corphish used Crabhammer which was a critical hit, knocking Growlithe out. Ash was able to convince Morrison to battle on, breaking him from his indecision. He sent out his Swampert, Corphish used Crabhammer while Swampert used Focus Punch, both being blocked and evenly matched, Corphish used Bubble Beam, while Swampert countered with Hydro Pump, with both attacks being blocked and evenly matched again. Corphish used Crabhammer while Swampert used Focus Punch again, both hitting and ending up with both Pokémon being knocked out, ending their battle in a tie.
In At the End of the Fray, Ash used Corphish as his third Pokémon in his Full Battle against Tyson in the Victory Tournament, it went up against his Hariyama, Corphish used Bubble Beam and Hariyama used Brick Break, but Corphish was able to get behind it and use Crabhammer, colliding with the Arm Thrust Pokémon's Focus Punch, this caused Corphish to be knocked out.
Back at Pallet Town in The Right Place and the Right Mime, it met and soon made friends with Ash's other crab-like Pokémon, Kingler.
In Tactics Theatrics!!, it teamed up with Swellow to battle Dome Ace Tucker and won Ash the Tactics Symbol.
In Talking a Good Game!, it battled Anabel's Alakazam and lost. In the next episode however, it was able to beat Alakazam in a rematch, only to be beaten by her Metagross.
Corphish danced with Brock to the same song as they did in Once in a Mawile, albeit a new version, in Strategy Tomorrow, Comedy Tonight.
Ash left Corphish at Professor Oak's lab when he left for Sinnoh.
It reappeared in An Old Family Blend!, alongside Ash's other Pokémon. It helped to battle against one of Team Rocket's mechas by using its Bubble Beam. It also helped to put out a fire, along with Totodile and Piplup, that was accidentally started by Cyndaquil. Corphish was not seen participating in the Lily of the Valley Conference.
Corphish was reunited with Ash in The Dream Continues!, where it and the rest of Ash's Pokémon posed in a group photo with him.