Counting Jigglypuff as a female might be cheating. I would say 1/9 of the original cast is female, disqualifying Pikachu, Jigglypuff, and Yoshi. They could pretty much go either way.
Counting Mewtwo as a villain is definitely cheating. He/it was never a villain in the games or the anime. The only reason Smashers treat it as one is because of its "badass" presentation and the event match in Melee where it is grouped with Giga Bowser and Ganondorf.
There are multiple protagonists who can double as villains more effectively than Mewtwo: Mario (Donkey Kong Jr), Samus (SA-X), Link (Dark Link), Lucario (Cynthia used one, making it part of a final boss battle), Charizard (same reason as Lucario but for first gen... if you picked Bulbasaur I guess), and even Mega Man (similar situation to SA-X or Dark Link, sometimes Mega Man is cloned and must fight himself).
