But Greninja doesn't have any relation to E3, and I doubt we're going to see anymore newcomers too after Sakurai went home, which means no Chrom, Shulk or Chorus Men there either, so I don't think it's limited to E3 knowledge. E3 was only mentioned in his first post too, and that was the 2013 version, never in his later posts.
Greninja doesn't have any relation to E3, you're right, but I bring up the argument because of this:
Essentially, Sakurai is saying there that they knew Greninja was going to be in the game, and the entire roster was finalized from the beginning of development. So unless the guy was sitting next to Sakurai the first few months and booted out on his ass for whatever reason, it stands to reason that he SHOULD know about Greninja (and by extension, Rosalina) and not say 'Pokemon from X and Y'. Why he says that? Who knows. We'll never likely find out.
Point is, the guy's proven he only has access to E3-related information (further proved by his change of the first leak's reveal of 'Mii' changing to 'Mii Fighter' literally hours before yesterday's event), which means that he doesn't have access to the entire roster.
Which means there's more to come in the final version, not including character DLC. So Ridley, and many others, have a genuine opportunity to wind up in the game at some point.
There y'go. Best summary I can give you.
If ChunkyBeef's theory is correct, then the newcomer to be revealed in August isn't set in stone yet. They could announce one of the three leaked characters currently unconfirmed OR announce a character that Sal Romano didn't have access to, like Rosaluma and keep the other three characters as unlockable/secrets in the game. For the love of Arceus, let Ridley be announced in August.
Or, it's entirely possible Sakurai learned from his mistakes with Brawl and intends to leave as much a secret with the roster as possible. It's certainly shaping up to be that way, honestly, and that's exciting to me.
Just had a thought about the whole stage hazard debacle. Remember how often Yellow Devil showed up on the stage during the Invitational? Assuming Ridley would have the same appearance rate, it must be a pain trying to keep him out of PotD shots and trailer footage unless they manually remove him from the stage for that purpose (not including the FD version).
Well, they have access to debug stuff, so I'd imagine it's as simple as toggling a variable to keep Ridley from appearing and turn off stage-related events.