At the beginning, I was only a Mewtwo supporter. I was bummed that he was cut from Brawl, and he was suffereing through a bout of irrelevance at that point. Yeah, he was terrible in Melee, but still, it was Mewtwo. I was with Pokémon when it started, and I don't care who they pull up now, Mewtwo will always be the most powerful Pokémon to me.
Since then, he's gotten a signature move (
Psystrike), TWO Mega Evolutions (the only Pokémon besides Charizard), one of which was used to tease MegaEvos, and been featured in two new movies. Mewtwo has regained his relevancy.
Going into SSB4, I was really pulling for Ganondorf and Mewtwo, but as I got into the characters more I started to support Ridley and K.Rool as well. The threads on this board really got me hyped up, to the point that if Ridley is not in the game, I'd actually be really bummed (not to mention that it would be a REALLY stupid business decision for Sakurai to tease Ridley for a year, only to piss off the fanbase right before release)
Point is, the big three are hands down the most requested characters in the entire fanbase, now that Megaman is in the game. We know Sakurai listens to fans (since Sonic was shoehorned into Brawl, causing Mewtwo to get the axe), so he should listen now. I think that Ridley is in, Mewtwo most likey, and K.Rool may be cut but be one of the first newcomers for DLC, after veterans like Wolf and (hopefully) Squirtle and Ivysaur return
The big 3 would make a lot of people happy with the roster, even with Dark Pit. And if most of the fanbase likes the roster, then you can say it's a favorite character game. End of story.
GO MEWTWO!
GO RIDLEY!
GO K.ROOL!