They'd tone her down, like they did with Snake in Brawl. Keep in mind that SSB is a teen-rated franchise, too.
Snake doesn't have a sexual appearance. It's easy to tone someone down by preventing them from using overly-violent animations. Besides, Bayonetta wouldn't be Bayonetta if she couldn't do half the things she does in the game, so she'd be a wasted character. Snake doesn't have to use guns to be Snake.
And you don't need to tell me SSB is teen-rated. Smash gets its rating by the violence, not by the content.
Edited by Press, 21 October 2012 - 09:19 AM.