Uhm... I see more and more people believing the leaker, but I'm still sceptical.
Correct me if I'm wrong, we know for sure he guessed Little Mac, Palutena, Mii and Pac-Man.
- Little Mac returned in the new Punch-Out for Wii.
- Palutena was teased to death. Sakurai also developed Kid Icarus Uprising. Furthermore, he said he was going to put more female characters in Smash 4.
- Mii is also playable in MKW, MK7, Mario Tennis, Mario Golf, basically every Nintendo character-based online game.
- Pac-Man is Namco's rep.
I don't count Greninja as an actual prediction -- every Smash introduced a Pokémon from the latest generation, and of course Smash 4 is no exception. He simply said "Pokémon from X/Y".
The hardly predictable characters are Villager, WFT, Shulk and Chorus Men. The first two were posted after their reveal. The latter remain to be seen.
And he completely failed to predict Rosalina.
In his first leak, where he listed ONLY SIX characters, the leaker included Wii Fit Trainer, Villager and Mega Man.
Think about that. If you were a faker, trying to make a list that might turn out right so that you could look clairvoyant after the fact, would you really waste one of your six guesses on Wii Fit Trainer, a character that literally
no one else on the Internet guessed?
Or Villager -- Sakurai had previously ruled out Villager, during the Brawl days, saying in an interview that Villager (and Nintendogs, and other such franchises) wouldn't work for playable characters since they don't lend themselves to fighting. As such, the dialogue among Smash fans at the time was that Villager stood no chance.
And then Mega Man... For all intents and purposes, MM and his franchise were considered "dead" before E3 2013. Many people thought he was unlikely since Capcom didn't seem to care about him anymore. Thus, he seemed unlikely from a "relevance" standpoint.
So if you were a faker... Would you really only guess six characters, and then make half of them THOSE characters? Btw, those three were confirmed within like 24 hours.
Any knowledge of probability whatsoever shows the odds of guessing that are astronomically low. That's like winning the lottery multiple times over.
Rosalina, meanwhile, was between leaks. Little Mac then came true, and later Pac-Man and Mii, as the leaker said.
A note about the Miis -- in the third leak, posted before the E3 Digital Event, the leaker correctly named the Miis as "Mii Fighters."
As for "Pokémon from X and Y," in the second leak, I think this vagueness is clearly attributed to the fact Greninja was chosen by Sakurai
before he even had a name. As Sakurai revealed at the roundtable after the Invitational, he chose Greninja based on his earliest reference drawings. It's quite possible the leaker saw Greninja back when he didn't yet have a name, hence "Pokémon from X and Y."
Also, the leaker is the only one to suggest Chorus Men, a Rhythm Heaven character, something uncommon on people's guess rosters. And guess what? A Rhythm Heaven character has since appeared as an enemy in Smash Run.
Everything is coming together. The leak is all but fully confirmed.