Since everybody has pointed out that Slowking will get catcher'ed, here is a suggestion: play catcher. Catcher would help this deck out a lot. Like Pikabruce said, a lot of decks can start OHKOing Mews early in the game. Forcing the opponent to waste energy on a Pokemon that is meant for the bench, like Vileplume or Emboar could give you the extra turns you need to win, or waste the opponents resources.