Woo!
Man, I am so jazzed. Glad to see that this has taken off as it has. I was really excited to read all of the suggestions, Mestro's in particular. Lots of great ideas for levels, and the clothing options were awesome.
Having the different clothing options but still having it say "Simon (Belmont) would work fine, I think. In SSBM, one of Peach's alts was the yellow dress, which is traditionally Daisy's color. The only problem I see would be the extra work involved in creating the different models in addition to the clothes. But we'll see either way, of course.
If there was only one representative "Castlevania" level, I would like to see a clocktower level. It's always just said, "Castlevania" to me, and has been a pretty consistant location in CV games. (I can't speak for all of them, because I've not played them all.)
I love the idea for the Castlevania symbol being the "whip power-up" symbol. It gets my vote, for sure. It's immediately identifiable with the series, completely unique, and unseen outside of the CV universe. All the other SSB symbols thus far have been preexisting imagery unique to the games that they represent. There have even been some obscure ones (Ice Climbers, for example) that most people who've never played the game would have no idea what it is.
Bottom line, reiterated: Simon Belmont is the initial representative of Castlevania, a Nintendo staple; one of the founding fathers of Nintendo. Castlevania has been an enduring universe, spanning multiple platforms, Nintendo and otherwise, and the Belmonts have been an central part of that universe. And according to the Wikipedia entry for Simon Belmont
http://en.wikipedia.org/wiki/Simon_Belmont, he's been a character in ten video games.
Simon Belmont FTW.
"I'm Simon Belmont, vampire hunter!"