Alright, this is what I've been preparing for all this time nominating Zero! LET'S ROCK AND ROLL! (Necessary Mega Man joke for good measure)
Zero - DWN-∞
Chances: 0.1% - Ha! No puns from THIS man! (Ironic, considering I'm fond of those). Really, despite all the controversy regarding him, and though I acknowledge he's pretty much a pipe dream, I still feel he's somewhat vaguely plausible. Though I'm sure the only way he'd manage to make it because of some miracle. That is, if Nintendo has secretly bought the rights to Mega Man, Sakurai is a merciful god AND the roster is in reality pretty damn expansive, allowing space for more characters than it is believed, including (possibly) Zero. All at the same time. Sadly, that's just as likely as Retro having secretly bought the rights to Banjo Kazooie a long time ago, as painful as that is to admit.
Want: 100% - What can I say? I bloody love Mega Man! And I adore the Mega Man X and Zero series (and may try out ZX some day). And, of course, I simply love Zero. In addition of being the living interpretation of the word badass, in both design and personality, he's one of the few characters that are so out of left field that just scream moveset potential.
Seriously, his buster-buster-slash combo from MMX2 can easily fit as a standard special, his Dash as a side special, his Rising attack, which he can pull off after a dash to perform his "Zero Final" combo, as well as the Earth Gaizer as his down special, his signature spinning slash (Kuuenzan) as a standard neutral, have the elemental attacks from MMX4 as his smash attacks (Raijingeki as Side Smash, Hyouretsuzan as Down Smash and Ryuenjin as Up Smash), etc.
HE'S JUST SO FREAKING AWESOME. That's all I want to say. And sorry for unleashing my fangasm so abruptly.
Holy Macaroni, Batman!
Chances: 15% - I'm not entirely sure what's up with everyone believing avatar-esque characters do stand a chance. I dunno, I don't think Sakurai would really consider anyone else from this category outside of Villager and PKMN Trainer (if he counts as such). Besides, in the world of Fire Emblem, there are many options, neither of which truly stand out from each other, perhaps with the exception Roy for being a veteran and Chrom for being recent. But really, they've all got relatively the same amount of chance as the other, as well as the chance of there being no 3rd Fire Emblem character.
Want: 2% - Lol, Roy bias.
Muddy Mole
Prediction: 4.78% - Obscure retros are so erratic when it comes to predicting.
NOMINAYTIONS
Okami Amaterasu x5