Well now you've done it; you've inspired me to make an account here and put my ¢2!
Considering Simon was CV's representative in those Wai wai world games, I'd say Simon has a shot at being in a smash bros title. Let's not forget that Konami HAS sprinkled him throughout the series. We got him in both HoD games--and in all his 8-bit glory I might add. As others have mentioned, Simon was in some other "smash" type of game, as well as Judgement. He was also in a sequel and some remakes earlier in his "career". And, considering he's in MoF (if I'm understanding correctly), he's never been far from Konami's mind.
And, as much as Smash bros. just LOVES to include virtually-clones of characters (I'm looking at you Dr. Mario, Toon Link, Ness/Lucas, and Marth/Roy), we have a shot of getting at least ONE Belmont (and I'll third, or fourth, or whatever it's up to) or a generic Belmont character with skins designating popular ones like Simon, Trevor, and Richter. Hell, they gave us fragging (pardon the Shadowrun parlance) Mr. Game and Watch, and animated him in such a style as to be an homage to his hand-held roots so we might get even get an 8-bit Simon. It certainly wouldn't be the first (or second) time 8-bit Simon has showed up.