I'm not sure if she is in Smash yet. But canonically, she easily is.
Bayonetta really isn't that tall, if Anarchy Reigns is anything to go by (the characters there have official heights. Bayonetta's is given in some made up "Umbran Witch" metric, but she's shorter than characters who are 6 feet tall). I believe she's like 5'8" there. Rosalina is canonically 7'7". Bayonetta just has absurdly long legs in proportion to the rest of her body, making her look super tall (also those huge heels give her a boost). Rosalina on the other hand, is just huge in every aspect.