This Seaking is a water-type Pokémon owned by Juan.
Seaking was used in the double battle round of his battle with Ash. It fought alongside Juan's Sealeo. During the battle it displayed the ability to use Horn Drill to deflect Pikachu's electric attacks. After defeating Snorunt with Hyper Beam, Seaking battled Pikachu and Corphish and was knocked out by Pikachu's Iron Tail.