Jellicent

Its body is mostly seawater. It's said there's a castle of ships Jellicent have sunk on the seafloor.

Ability — Spiteful Spirit: If this Pokémon is your Active Pokémon and is Knocked Out by damage from an opponent’s attack, the Attacking Pokémon is now Confused and Poisoned.

Aqua Bullet (40): Does 10 damage to 1 of your opponent's Benched Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.)