Dark Croconaw

It has 49 teeth in its mouth that are constantly replacing themselves. Pull one out, and a new one grows in.

Clamping Jaw (20): The Defending Pokémon can't retreat during your opponent's next turn. If the Defending Pokémon tries to attack during your opponent's next turn, your opponent flips a coin. If tails, that attack does nothing. (Benching either Pokémon ends this effect.)