Krabby is a Water-type Pokémon from Generation I. It evolves into Kingler starting at level 28.
In the anime, Ash, jealous of Gary's massive Krabby, captured a Krabby in the episode "Mystery at the Lighthouse", but left it with Oak for a while after realizing it was tiny compared to Gary's. Ash did not use Krabby until "Round One - Begin!", where Krabby was able to defeat Mandi's Exeggutor before evolving into Kingler, where it defeated Mandi's Seadra and Golbat, allowing Ash to continue the Pokémon League Tournament.