Mewtwo

Mewtwo feels less like a Pokémon you stumble across and more like something you were never supposed to encounter. That sense of danger is a huge part of the appeal. Where Pikachu wins people over with personality and Eevee with attachment, Mewtwo walks into the bracket carrying pure menace. Put it against Charizard and suddenly two of the most intimidating names in the field have to share one card. Put it against Pikachu and the entire argument changes: overwhelming power versus the companion everybody recognizes. Mewtwo has an easy case for being one of the most formidable contenders here. Whether that makes it the greatest is up to the voters.