If we're talking Paper Mario, I just want a game where the entire cast isn't replaced with bland ass Toads again.
One thing I'm sure of is that characters from 3D fighters are probably not going to get in, mainly because of the sheer difficulty Sakurai has of recreating their moveset faithfully into Smash.
And there's a fighting game character I'm surprised is hardly mentioned who I think is the next fighting game rep that definitely has a good shot and Video Game legacy.
He mentioned difficulty with Heihachi in particular. But the fact that Sakurai was clearly interested in the first place shows there's a small chance I think. I guess it depends on whether or not he can figure out how to implement the Z-Axis for a Smash character. Also, he could take a different approach when implementing them. Say maybe make the character rely more on combo strings. It'd be really different if say, Heihachi could use AAA, AAB, ABA, and ABB for different attacks all based on his vast moveset.
In the case of Sol, he's mentioned a few times. And if ArcSys got a character, he's a vastly better choice than Ragna. But I don't exactly know what Guilty Gear's popularity's at. SF's popular in the US/Japan/Korea, Tekken's popular, especially in US/Japan/Korea, MK's popular in NA/EU, SNK's got the Latin and Chinese markets.
GG's popular mostly in Japan, but it's competing with Tekken and Street Fighter.
Sol would be cool, just not my first choice.