Buizel

“It has a flotation sac that is like an inflatable collar. It floats on water with its head out.”

— Pokémon Diamond

“It swims by rotating its two tails like a screw. When it dives, its flotation sac collapses.”

— Pokémon Pearl

“It spins its two tails like a screw to propel itself through water. The tails also slice clinging seaweed.”

— Pokémon Platinum