Ash originally obtained it as a Krabby in Mystery at the Lighthouse, where he became angry at Misty for her saying that it was not a fluke that he captured all his other Pokémon. Storming down to the beach, he discovered a minuscule Krabby and then made fun of it. Krabby challenged Ash, who fought it with a nearby stick and then captured it in a Poké Ball. Having six Pokémon already in his party at the time, the newly caught Krabby's Poké Ball was teleported away, much to Ash's surprise and concern. He soon learned that Krabby was sent to Professor Oak.
Ash quickly rang Oak and became horrified that he thought Oak was eating his new Krabby. However, he became relieved that Oak was actually eating tofu and that Krabby was quite happy at Oak's lab. However, the happiness he felt at capturing his seventh Pokémon wore off as soon as Oak revealed that Gary had also captured a Krabby, although his was far larger in size. Gary later mocked Krabby himself in Showdown at the Po-ké Corral, degrading Krabby in comparison to his own.
Krabby's battling debut came in Round One - Begin!, when Ash used it during the first round of the Pokémon League against Mandi. He reasoned that Krabby would be perfect for a battle on the Water field despite Misty's protests that Ash should borrow one of her Pokémon as Krabby had never battled before. Ash retorted that he still had Squirtle and Pikachu as backups should Krabby fail.
It seemed at first that Misty's forebodings would prove true; Mandi's Exeggutor used Psychic to trap Krabby in a Whirlpool. However, Krabby managed to escape and took control of the battle with ViceGrip. It avoided Exeggutor's Hypnosis and took victory with Leer and Stomp. The intensity of the battle causing it to evolve into a Kingler. It was able to finish the rest of the match single-handedly, defeating Mandi's Seadra by slowing it down with Bubble and then knocking it out with Crabhammer, and then taking out his Golbat with a Hyper Beam. This was despite Misty and Brock's real concerns about Kingler's ability to prevail against Seadra's speed and Golbat's air attacks.
Ash also used Kingler in his battle on the Ice field in Fire and Ice, where Kingler defeated Pete Pebbleman's Cloyster by hammering repeatedly on its shell with Crabhammer until it fainted. It then fought his Arcanine, but its Bubble was dodged by the Fire-type Pokémon, and then it was knocked out by Dragon Rage.
Kingler spent most of the time at Oak's lab as Ash and his friends traveled the Orange Islands. Muk and Kingler offered to fight for Ash in the Orange Island Championship battle against Drake in Hello, Pummelo!, but Ash chose Tauros instead.
Ash used Kingler in Johto during the Whirl Cup tournament in The Perfect Match, when Ash realized that he only had a single Water-type Pokémon, Totodile. He sent Bayleef to Oak's lab and Kingler joined his team. In the second round, after Totodile's loss to Poliwhirl, Kingler knocked out Poliwhirl with a powerful one-two punch Crabhammer. However, when Ash ordered it to use ViceGrip on Psyduck, the pain gave Psyduck the ability to tap into its psychic powers and defeat Kingler with a Confusion attack. Kingler was sent back to Oak's lab afterwards.
In Love, Pokémon Style, Ash planned to use Kingler in the Johto League Silver Conference against Macy's array of Fire Pokémon, but it was injured while rescuing a trio of runaway Voltorb, who shocked Kingler when it caught them. Ash was later informed that Kingler would not be able to compete in the battle, but Squirtle arrived in time to fill Kingler's spot.
In Showdown at the Oak Corral, Kingler made a cameo appearance telling the other Pokémon about Cassidy and Butch.
Kingler currently resides at Professor Oak's Lab, where it quickly made friends with Ash's Corphish in The Right Place and the Right Mime.