Cubone

Because it never removes its skull helmet, no one has ever seen this Pokemon's real face. In "The School of Hard Knocks," Giselle, a stuck-up student at Pokemon Tech, battles Ash and Pikachu with her well-trained Cubone. Pikachu battles valiantly, but Cubone is merciless. After using a strategy that the book-smart Giselle can't figure out, Pikachu tricks Cubone into getting hit on the head by its own Boomerang attack!

First appearance: Episode 9—"The School of Hard Knocks"