Gyarados

Once it appears, it goes on a rampage. It remains enraged until it demolishes everything around it.

Ability — Untamed One: When you play this Pokémon from your hand to evolve 1 of your Pokémon during your turn, you must discard the top 5 cards of your deck.

Hyper Beam (200): Discard an Energy from your opponent's Active Pokémon.