The Gardevoir leak and Skull Kid hints are throwing everything off; that points to not every newcomer being a highly-requested one, which would be a shame. Like why not just go all-in with fan requests? It's kinda like stages: they were so close, but left a few out.
I mean, common sense is telling me the final newcomers will be Gardevoir, Gothitelle, Shadow, Isabelle, Skull Kid, maybe Incineroar... take your pick from Geno, Dixie, Isaac, Bandana Dee and Banjo (these shoulda been automatics) to round that out; someone's feelings are gonna end up being hurt. I do not think all of those will get in.
I mean, everything has been so unpredictable I've kinda just given up on predicting newcomers in general; it's fun to speculate, but there are always curveballs. Sakurai acted like Dark Samus and Chrom were shoe-ins, but those two surprised me more than Simon, K. Rool and even Richter. Gardevoir scares me he could go back to his old ways: this is a character I and a lot of other people like, but this isn't even a top 20 requested newcomer.
This is so important; I like Mach Rider (especially with Sakurai buying that gun). Anything else would be a stretch (which is completely plausible), but I'm also thinking something like Diskun that I don't even know what it is.