I am going to speculate the full roster for the game, which includes already confirmed characters and other speculated characters...

Mario (Mario, Luigi, Princess Peach, Bowser, Yoshi, Geno) A pretty good choice, I also think Rosalina could make the cut as well judging her sudden popularity increase in the last two years.
Wario (Wario, Ashley) Possible, but I doubt the SSF2-dev team would consider a character who is already appearing in Crusade. Captain Syrup, Jimmy T., 9-Volt or Mona would be good additions to the Wario universe as well.
Donkey Kong (Donkey Kong, Diddy Kong, King K. Rool) If we got Isaac, we need K. Rool. He's been a popular demanded character for so long, and also a unique one so I agree with this choice.
Kirby (Kirby, King Dedede, Meta Knight)
Zelda (Link, Zelda/Sheik, Ganondorf, Young Link) Would rather prefer to have Skull Kid over Young Link, but if he gets a brand new moveset then I'm good with it.
Pokemon (Pikachu, Jigglypuff, Lucario, Mewtwo) Most likely we'll see both of these join, but I think we're getting a certain character from the Pokemon universe to join as well...
StarFox (Fox, Falco) No Krystal?
Metroid (Samus, Zero Suit Samus)
F-Zero (Captain Falcon)
Mother/Earthbound (Ness, Lucas) Ness is enough.
Fire Emblem (Marth, Ike, Roy) Lyn and/or Hector have more potential than these two IMO. (Lyn w/ moves regarding her Bow, and Hector is able to wield axes.)
Kid Icarus (Pit)
Golden Sun (Isaac)
Game & Watch (Mr. Game & Watch)
Pikmin (Olimar) Maybe. Not sure how the devs would be able to code the Pikmin in this game.
Punch-Out! (Little Mac) Highly likely.
Animal Crossing (Villager) Very unlikely.
Xenoblade Chronicles (Shulk) Same as above.
Misc. Nintendo (Chibi-Robo, Ice Climbers (Hopefully revealed at Smash-Con), R.O.B., Andy or Sami, Lip) Ice Climbers are likely due to the fact we have a hidden stage in the code of the game not yet revealed. An Advance Wars rep would be so cool and fresh to add to a Smash Bros. game. Lip doesn't have that high of a chance to make the cut, but still possible.
Sonic The Hedgehog (Sonic, Tails, Knuckles, Shadow) Silver is an assist trophy. These two are making it for sure, and if not then I don't know how the Sonic fandom will take it lol.
Super Smash Bros. (Sandbag)
Mega Man (Mega Man, Zero) As a fan of the Mega Man Zero series, I so agree with Zero making the cut! But is not likely.
Street Fighter (Ryu) Possible.
PAC-MAN (Pac-Man)
Tales Of Symphonia (Lloyd Irving)
Metal Gear Solid (Snake)
Castlevania (Simon Belmont) Either him or Snake. Having both would be cool to see though.
Bomberman (Bomberman)
Final Fantasy (Black Mage, Cloud Strife) 'Appears in at least one Nintendo console game' rule negates his entry to SSF2.
Kingdom Hearts (Sora)
Chrono Trigger (Crono) Unlikely, but would love to see him come back.
Shonen Jump (Goku, Ichigo, Naruto, Monkey D. Luffy) No more anime characters. Adding to that, they want to make this game professional. The first three are only still in because if they were cut out of the game, all that hard work the devs put into each character would go to waste. (and also to please fans from each of the respective franchises)

Notes: The characters in Bold are characters who have yet to be confirmed and Bold-Italicized are speculated to be unlockable. While this is NOT a real roster at all, this is pure speculation. In actuality, I think we will get anywhere from 55-60 characters. Let me hear what you guys think!

Cloud Strife) 'Appears in at least one Nintendo console game' rule negates his entry to SSF2.

Just remember the roster was set in stone sometime around 2010-2011, a time where Cloud wasn't even close to appear in a Smash Bros. game, but we'll see.

It was actually March 2013 that the roster was locked and sealed.

If no one minds, I'd like to try my hand at speculating the full roster (Not counting future DLC)

Mario (Mario, Luigi, Princess Peach, Bowser, Waluigi, Princess Daisy, Rosalina, Bowser Jr.)
Donkey Kong (Donkey Kong, Diddy Kong, Dixie Kong, King K. Rool) If I had to pick between Dixie Kong and King K. Rool, It would be K. Rool because Gangplank Galleon being in the game & he deserves a spot in Smash.
Wario (Wario, Ashley, Mona) Ashley would be an awesome character as she uses her magic while Mona would be an AT to me.
Yoshi (Yoshi)
The Legend of Zelda (Link, Princess Zelda, Sheik, Ganondorf, Young Link, Skull Kid) Skull Kid or Young Link would be pleasable candidates.
Kirby (Kirby, Meta Knight, King Dedede, Bandana Dee, Adeleine) Bandana Dee is an Assist Trophy, but if Pac-Man can "Break The Trophy", then so can Bandana Dee! Adeleine would be awesome, but is highly unlikely.
Pokemon (Pikachu, Jigglypuff, PKMN Trainer, Mewtwo, Lucario) A Pokemon Trainer would be decent.
Metroid (Samus, Zero Suit Samus, Ridley) Ridley CAN be playable in SSF2.
Star Fox (Fox, Falco, Krystal, Wolf) Falco will probably be the only one we get.
F-Zero (Captain Falcon)
EarthBound/MOTHER (Ness, Lucas, Ninten) Ninten would seem like a clone of Ness. Lucas would be a better pick because he was a veteran in the Smash games plus he is heavily requested around here.
Fire Emblem (Marth, Roy, Ike, Lyn) We are most likely getting one more FE rep and if I had to pick one, I would pick Roy.
Kid Icarus (Pit, Palutena) Pit will most likely be the only KI rep until DLC.
Golden Sun (Isaac)
Pikmin (Captain Olimar)
Punch-Out (Little Mac)
Animal Crossing (Isabelle) No.
Game and Watch (Mr. Game and Watch)
Misc. (Chibi-Robo, Ice Climbers, R.O.B., Andy, Sami, Lip, Ray MK III, Saki Amamiya) Personally, Sami would be a better Advance Wars rep than Andy, but since he is the main character, he will most likely be the representative for Advance Wars. Lip would be an amazing rep from the West exclusive to SSF2. I think Ray MK III would be a great addition to the roster. I am curious to see what Saki's moveset will be.
Sonic the Hedgehog (Sonic, Tails, Knuckles, Shadow, Amy) Way too many Sonic characters in this list. Might as well call this Sonic Smash Flash 2 lol. In all seriousness though, Knuckles and Shadow will either both make the cut or one will make the cut and one will be cut from the initlal roster.
Mega Man (Mega Man, Zero, Roll) I would love to see both Roll and Zero make the cut, but in all honesty, Zero will get in.
PAC-MAN (PAC-MAN)
Tales (Lloyd, Kratos) I am pretty sure that Kratos Aurion will not be making the final cut.
Metal Gear (Solid Snake)
Castlevania (Simon Belmont)
Bomberman (Bomberman)
Final Fantasy (Black Mage, Cloud)
Kingdom Hearts (Sora)
Shonen Jump (Goku, Naruto, Ichigo) I have a 50/50 feeling that Luffy might make the roster.

Italicized names are unlockable.

You're both wrong. Pac-Man and Sandbag prove that the roster's not sealed anymore.
The former was just announced for Smash 4 just before the release of v0.9b (and, thus, just before the first sign of Beta was revealed). I seriously doubt that he was always intended to be playable, considering they bothered coding him in as an assist trophy in the first place.
The latter was confirmed to have started out as a silly little personal pet project by TSON that they decided to keep in.

^The devs love messing with us though, haven't you realized by now?

^The devs love messing with us though, haven't you realized by now?

Totally aware of that. I hope they see this and realize how crazy they're driving us haha.

Back to speculation, I wanna see a character from well-received Nintendo franchises that has a lot of potential such as Daisy Dillon from Dillon's Rolling Western or Andy/Sami from Advance Wars to be playable in SSF2.