Okay, let me make this one thing abundantly clear for ALL of you: While the gematsu leak is has an 8/11 ratio, it doesn't mean that it is beyond a shadow of a doubt, completely true! In fact, if one looks at the villainous trifecta that are King K. Rool, Ridley, and Mewtwo, all three of them have more evidence supporting them than freaking Shulk, may it be from Sakurai himself or from some gameplay footage! Heck, one could even make the argument that the evidence supporting Ridley being playable in particular is far stronger than ANY of the gematsu three. Why? Here's the actual hints for all six of them:
Ridley: We know he is in the game. That much has been confirmed beyond a shadow of a doubt. His role was teased. Pyrosphere--one of the oldest stages revealed during Smash 4's development--wasn't at all playable. And Sakurai has made it abundantly clear that he doesn't like to tease fans into false alarms concerning ANYONE but playable characters. And what makes people think that Ridley cannot fill both of these roles considering the fact that Ridley in Other M (where Pyrosphere comes from) was a clone of the REAL Ridley (the one that we saw in Brawl)?
King K. Rool: The Kremling enemies in Smash Run, again, suggests that K. Rool will play a role in Smash Brothers beyond just being a trophy. The fact that he was never disconfirmed outright suggests that he could very well be playable. Granted, that is about as big a stretch as I am willing to go concerning newcomers based on hints; any further, and even Dark Pit technically has more evidence going in his favor than Shulk, and I don't even think THAT's going to happen.
Mewtwo: At E3 2012, when the roster was finalized, Sakurai said concerning Mega Mewtwo Y, "We are thinking about it!" While we cannot treat this as absolute truth that he will be in the game, at the very least, we can expect that the character will have been worked on. Even if he isn't playable in the final version, if the character DLC is to mean anything (it's so obviously going to be done through the Amiibos that it's not even funny), he'd be one of the very first characters to be considered along with Lucas and Captain Toad (who was disconfirmed from the final roster, but is hinted at as potential future DLC), and I'd even go so far as to predict a reveal that'd coincide with Pokémon Omega Ruby and Alpha Sapphire if that is to be the case.
So of these three, the winner by a large margin is Ridley, followed by Mewtwo (final roster or DLC), and lastly, King K. Rool. Now let's check out the evidence supporting the gematsu three (and no, the leak itself does not count; I'm talking about official details, here):
Shulk: Well...his voice actor said he'd get castrated if he revealed the roles he finished for this year prematurely. And, uh...the creator of Xenoblade retweeted concerning the big reveal. And, uhh...Mechon trophies were rumored on gamefaqs to be found in Smash Run? Let's be honest, you die-hard gematsu worshippers! This guy's got jack for evidence being in the game. Granted, you could argue that that's for the best since any hints would flat out give the character away, and that's for the best. But it could just as easily stated that this could very well mean that there will be little to no Xenoblade-related content in the final package! Fan demand, the gematsu leak, and a few unreliable rumors are all he has going for him. And if this little tidbit of evidence coming from the creator and the voice actor is to have any merit at all, then Shulk will HAVE to be revealed Monday. Otherwise, I'd be hard-pressed until the release of the game to believe that he will at all be playable.
Chrom: Well...Arena Ferox! But aside from that, there's also little to nothing indicating that he'd be playable. And even if that one stage is to be looked at as evidence, then surely, there'd be a larger selection to choose from. For all we know, we could get Lucina or Robin instead for all I know. Heck, people have speculated other characters outside of those three from Fire Emblem: Awakening. This pretty much means that any character reveal from that game that isn't Chrom will instantly disconfirm the leak. End of story.
Chorus Kids: Of the remaining three characters, they are the only one that actually has concrete evidence in the form of the Sneaky Spirit enemies in Smash Run. Barring the SSE enemies themselves, every enemy in Smash Run revealed so far has had direct ties to a franchise already represented by at least one playable character. The one exception is with the Namco enemies, and one could make the argument that Pac-Man is essentially a playable Namco museum in and of itself. The problem here is that it only confirms a playable Rhythm Heaven character, and that there are still highly possible alternatives in the form of the reporter, the wrestler, Karate Joe, or the lone Marshall. I do believe that if the Chorus Kids are playable, they would take on their appearance in Rhythm Heaven Fever, but we also have the Ice Climbers problem on the 3DS version as well. We don't know how they'll play if they will be playable. We just know that we will be getting a Rhythm Heaven character.
So, in the order of likelihood: Chorus Kids is the most likely but not set in stone, followed up by Chrom who also isn't set in stone either, and then finally Shulk, who has absolutely no solid ground in his favor so far. Matched up with the villainous three above, and the order would go like this: Ridley, Chorus Kids, Mewtwo, King K. Rool, Chrom, and finally, Shulk in descending order. And no, the gematsu leak doesn't give the three an added bonus since it's just a leak. A highly accurate leak, but it isn't the final word on the matter, and can still be proven fake. Just one misstep is all it takes.
Now what about other characters? Again, Captain Toad was disconfirmed with a poster with him dreaming of someday being able to join the fight (which could potentially hint towards him being revealed as DLC). Dixie Kong, I feel her ship may have sailed long ago, but could survive as DLC (or as an alternate selection over King K. Rool). Impa and Ghirahim only have the Trophy Quiz going for them, and even then, I predict at least one of them either on the roster or as DLC. Dark Pit is a solid maybe, but even taking into consideration DLC, I figure Hades is a much more likely option. We already have all the significant Kirby characters present; we don't need Bandana Dee added as well. Fox, Falco, and Wolf are all fine representing Star Fox as is, so we have no need for Krystal (as unique as her moveset could potentially be). Sceptile is a virtual impossibility; if Mewtwo isn't already present, he'll be DLC; if he is, then Blaziken makes the most sense to represent Hoenn. Roy and Lucas are the only possible choices for DLC character from their respective franchises. And Snake might happen only if Sakurai and Kojima consent on the matter (and even then, only as DLC).
As for these two recurring newcomers: Both Takamaru and Isaac are a bit of a stretch. I feel Takamaru became big mostly due to the fact that I think his interest grew from a leak that stated that Little Mac and Takamaru would signify an East vs. West motif (whatever it was, it was disconfirmed a long time ago) as well as a desire from Sakurai to include more retro characters, and that beyond all that, he seems to have a bit of a far-shot at getting in. Isaac, I feel people tend to forget that Golden Sun is second party, and with the exceptions of Pokémon and Kirby (both for obvious reasons), Smash has never had another new representative from a second-party developer; Sonic's borderline, and even then can still be considered a Guest character. Add to that that Isaac's AT required 200 brawls at least to unlock, I do believe it isn't too much of a stretch that his AT will be held back until after launch.