My character chances:
Ridley/K. Rool/Little Mac - 99.9%: All are among the last few Nintendo All-Stars remaining, with the previous two far and away being the most important characters left from existing series, while the latter has priority among new franchises due to his revival and popularity.
Mewtwo/Roy - 95%: Are intensely popular, and barring advertisement characters receiving priority, they'll get in.
Palutena - 85%: A popular request, primarily in Japan. Sakurai's modesty was seen in Melee but certainly not in Brawl, so that's a toss-up in my eyes. Her fanbase is also less solidified than any of the above characters, but she is SSB4's number one female anyways.
Megaman - 75%: Far and away the most likely third party character.
Takamaru - 75%: Retro spots are difficult to predict, though he easily has the credentials needed to earn his place.
Bowser Jr./Dixie - 50%: Both are easy Luigified clones to add, but may not take immediate priority within their own franchises.
Toad - 50%: Has recency and seniority in his favor, but faces fierce competition and is not requested -as a character- in Japan.
Advertisement Pokemon/New Lord: Very dependent on the requests of their companies and Sakurai's inclination to add new characters, since no advertisement matches the cut veterans' popularity.
I believe those characters have the best chances, followed probably by Krystal, an F-Zero character, Bandana Dee or a Zelda one-off. Oh, and probably one or two blonde-haired swordsmen, all of whom are extremely difficult to analyze, due to their latest games flopping, competition from each other, from their own sons, or being from a single niche game.
