On the Sal leak, I don't think it's false, but I'm also not convinced it's 100% correct. There's unfortunately no way to tell unless Sal gets more information from his informant.
Here's my take on it: The guy who is leaking information to Sal works in the game industry, possibly for Nintendo or Namco, but isn't close enough with the development team to get information firsthand, or regularly. Why is it we've only gotten these leaks from him right around major events? I believe it's because this guy only gets information around these events, and never any other time.
That said, he's probably not getting his information early as we're thinking about it. Maybe he's a video editor or visualizer, or just works in a press room. He's probably seeing this stuff mere hours before it gets presented to the public, and otherwise has no access to it.
My theory is that he's going into a presentation room with press or a preview group, seeing the information ahead of time, and then reporting it to Sal as soon as possible in order to get the information out. More than likely he's not allowed to have a cell phone or camera in the room with him, so if he's not a fan of Pokemon, that might explain the vagueness of "a Pokemon from X and Y." The guy might have heard and seen Greninja's reveal, but not really having an interest or playing Pokemon, after the presentation could not remember the name of the Pokemon that was revealed, instead just remembering that it was something from that new X and Y game.
This is my theory. It may be right or it may not be. That's why it's a theory. But for me, it makes sense. After working in the gaming industry for years, I know companies tend to keep things hush hush, but they do reveal info to other companies, magazines, and the press before they reveal it to the public. Sometimes it's an hour before, sometimes it's a day before.
But the fact remains that certain people get this info early, and Sal's leaker has never given us this information far and beyond the amount I figure the press would have access to it. This tells me his leaker possibly doesn't work for Nintendo or Namco, but is instead simply getting a sneak peak and reporting it to Sal in order to be credible.
What's that say about the remaining characters he has predicted but have not been revealed, like Miis, Pac-Man, Shulk, Marshal, etc.? That's where I'm reserving judgement. It's possible they mention these characters at these press events and just ask people not to say anything to the public or perhaps make them sign a form, but that seems incredibly unlikely. It's also possible that Sal's informant works slightly closer to Nintendo or Namco to get inside info himself during these events, and is thus reporting them along with the official characters revealed. Or he could be making them up alongside the actual characters in order to get speculation going.
That's why I'm reserving judgement. I want to believe the Sal leaks as I think they make a fun and unique roster, but nothing is 100% official unless Sakurai says it is. While Wii Fit Trainer, Mega Man, and Villager might have been hard to predict weeks or months before E3 last year, they would not have been hard to predict hours or even a day before the event for someone working there or in the press, in my opinion, because that information would be floating around prior to the event. And unless someone can correct me here, I believe Sal got his first leak just shy of a day before E3. With this second leak just hours before the direct, I'm inclined to draw the theories I've just posted.
Whew. Sorry for the massive post, but read it and let me know if you think it sounds likely.
tl;dr version: Sal's informant may merely have access to information a few hours earlier than the public does, so while some of his info is correct, the rest may or may not be. Take it with a grain of salt.