Board Thread:Super Smash Bros. Discussion/@comment-14750692-20140617071306/@comment-16072884-20140617122425

Pokémon, being arguably Nintendo's second-biggest franchise after Mario, is actually pretty underrepresented with just 5 in a cast of 50+ characters. I think Mewtwo will be the sixth Pokémon to join, and Sakurai is just waiting till later to reveal him.