Dialga

Overview
Dialga is a Mythical Rarity Card. Although not impressive with it's statline, it's ability stands out. Basically all Fainted Pokémon, you and your opponent's Pokémon, go back to their respective decks. Not only you can reuse these cards again, but they are good to counter against any card that has abilities that correlate with the count of Fainted Pokémon, like Houndoom and Ultra Necrozma.