This is what I think:
Since Nintendo says that they will add 3DS exclusive stages to the 3DS game, and Resident Evil: The Mercenaries 3D and Resident Evil: Revelations appears on the 3DS. If there is a Resident Evil stage, like the Queen Zenobia or The Village, most likely Chris Redfield will appear as a version exclusive character.
If there are Resident Evil stages for the Wii U version, since they base the stages from the Wii and WiiU games, Leon S. Kennedy will likely appear as the Resident Evil version exclusive character.
I also think that Pac-Man and Seigfried Schtauffen (Or Sophitia Alexandra) will likely appear in the game. More so Pac-Man will be a (or the) Namco representative.
I also think that Rosalina will be a new Mario representative. I also think that Ghirahim will be most likely to replace Ganondorf (if he does not get in).
But anyways, I also think about these characters as newcomers, from most likely to least likely:
Rosalina/Ghirahim/Zoroark
Pac-Man
Palutena
King K. Rool
Banjo Kazooie
Chris Redfield/Jill Valentine
Vaati/Nabooru/Demise
PKMN Trainer Gold
Goku
Seigfried Schtauffen/Sophitia Alexandra
Trainer Red (He is NOT the same guy from Brawl, just remarking)
Shadow the Hedgehog/Knuckles/Tails/Zero/Waddle Dee
Leon S. Kennedy
Raichu
Dark Link
Takamaru
Saki
Mach Rider
Krystal
Ichigo Kurosaki
Naruto Uzumaki
Master Chief
Jack Krauser
Slender Man *snickers*
Dixie Kong
The characters are highlighted all have are fairly likely to average likeliness.
Takamaru is the top pick for a Retro representative since him and his franchise has recieved a lot of love recently from Nintendo.
While I wouldn't consider Saki very likely (:tear: ), I would place him above many of the 3rd party characters you mentioned as well as Raichu, Dark Link, and the Pokemon trainers you listed.
Same goes with Krystal. I am not a big fan of hers but she is still more likely compared to Goku, Chris, or even Banjo due to them being 4th/3rd party.
Mach Rider is a fairly popular and requested Retro character that usually ranks right behind Takamaru in most polls.
Finally, due to Dixie Kong's surge in both relevancy and popularity due to the recently announced DKC for the Wii U, many consider her likeliness to be on par with King K. Rool or even greater.
As well, those three you put up Rosalina, Ghirahim, and Zoroark have average to above average chances; often shown in most polls. However, I would not consider them very likely.
I just felt like pointing those out. I would say that any 4th party character has a 0% chance of appearing while 3rd party companies unrelated to Nintendo (Slenderman, Master Chief, and, technically, Banjo-Kazooie) also have a 0% chance (though I would rank Banjo a bit higher but I highly doubt he could get in.) Finally, a second capcom representative is also unlikely due to Megaman's inclusion. If we got more than one character from a company, we may have seen Shadow or Raiden in SSBB but we didn't. In addition, Sakurai is pretty picky with adding 3rd party characters. Prior to Megaman getting in, we had no idea if they would include a 3rd party character again. So I doubt we will see a Resident Evil character due to the unspoken rule of "One character per one company".
Capcom is definitely helping with SSB4
Source please.
Oh, and both the Wii U and the 3DS will have the same amount of characters. So, that debunks your Chris/Jill being only on the 3DS argument.