I argue that Gematsu is saying a lot more than it lets on. Sure, it may only specifically name a fair amount of newcomers on the surface, but deeper down, there's more to it. The reason I think this is because of the mention of the Ness and Lucas dilemma. Why mention that specifically, and not anything about PT's pokemon or Snake? I believe the leaker did have information on them and Rosalina, but Nintendo and/or circumstances surrounding the characters simply beat them to it. Think about it.
- PT's removal is unmentioned because it's pretty well implied and covered in the April 8th Smash Direct that he's gone along with his two 'mons.
- Snake's removal is unmentioned because it's fairly clear by Kojima's and Sakurai's words that Snake simply isn't in(and the state of Nintendo and Konami's relationship is... Poor).
- Lucas's removal wasn't hinted at or clear by any circumstance, so the leaker saw fit to disseminate information relating to his(very likely) cut from Smash.
Rosalina similarly goes unmentioned because there she was already confirmed. Why include her on a list of newcomers? You'll notice that none of the other predictions that were confirmed were on Part 2 either. Why not just expand the list rather than type out a brand new one? Because I believe this list is only mentioning things that are significant changes to the game that are not immediately clear due to other information. This is why the leak doesn't mention Mewtwo, Ridley, or any of the Big Three, because the status quo(they're not playable) is being maintained in those regards.