I disagree on them being a Fighting character doesn't make them fit(when Mortal Kombat can make useless characters like Mokap playable... who is just the guy who does the Motion Capture system in real life...), however, we already have a Capcom character in, so I don't see any Street Fighter character relevant at this point anyway. But other companies? Something to think about. Or could've been. It's sad to see that view, though. I don't see why that makes any difference in the end. I mean, sure, he did purposely base MegaMan off of something besides his MvC self(which I'm glad he did, since him being a shotoclone is what kept him out of MvC3... when Akuma stayed in. -_-), but it doesn't mean others would've been weird regardless of their genre origin. Sonic got at least two moves from the fighting games he was in(his Air Down A is a very similar to Shadow Rocket in Sonic Battle, and one of his throws is a carbon copy from Sonic The Fighters)
Anyway, it does narrow down the list of potential third party characters, so we know a bit more what to expect. Too bad for Soul Calibur, though. I wasn't fond of Tekken(even if they could have some interesting additions, like Yoshimitsu, since he spans two fighting series, legacy-wise).
@Arcadenik: I wouldn't even expect Toon Ganondorf in at this point, unless Toon Link is switched out, and that Toon Zelda doesn't appear, despite plans. I want him too, but he still is not like Lloyd, so that doesn't matter. As for Roy, it's not that well known he could have two swords, since a lot haven't played his game, unlike Symphonia OR Wind Waker. So no, I really don't see either of them being matter in that regard. Roy, if he were to come back, may still be similar to Marth again. Ganondorf? I expect his TP form with SS-style coloring like TP Link has in For.