Arqua

Arqua is East Kai's prodigy student. He is matched against Goku in the third round of the Other World Tournament, where he is met with a rough start. Shortly into the match, Arqua transforms the arena into a water environment, giving him somewhat of an advantage in the battle. He makes his debut in the 197th episode of Dragon Ball Z, "Water Fight", and he is seen again in a cameo in the movie Dragon Ball Z: Fusion Reborn.

(Source: Dragon Ball Wikia)