I never really played Smash Bros that much so when it came to my first time playing it my girlfriend (who absolutely loves the game and used to play it lots) completely and utterly wiped the floor with me (it's alright though, she needed me to complete Goldeneye for her so I can still safely say I'm better at shooters).
But back to the topic at hand, yes, girls do like Smash Bros just as much as guys (given it's bright, colourful look, laid back and casual mood and simple gameplay I can't really imagine why it would exclude anyone).