I'm with you on this. For me, am currently not too sure what to expect, but I do expect a first party character too. To me it's a toss up between a Zelda character, a Pokemon, and Isaac. All would make a lot of sense retrospectively, and this Fighters Pass so far has been all about reconsidered ideas.
Yeah same! Those three are the only ones I can viably think of. Beyond that there's Advance Wars or Kirby reps but I think they're less likely. I'm basically thinking anything released 2018 or after is probably not getting considered, because it's hard to plan and design a character that's halfway through development. The exception being Pokémon where Sakurai can go off concept art apparently.
It's still hard to settle on a character though. Zelda's best side characters are all assist trophies, so we're left with BotW Champions or Age of Calamity fighters. Eh? Possible, but I wouldn't be that psyched. I'm only really going off the fact that Ultimate Link is a BotW remodel, so it barely counts as a new Zelda rep, even though that's what it's meant to be.
Pokémon absolutely shouldn't be in this position. They've already had a rep in Ultimate. Granted there's no new stage, but we haven't seen a double dip of a franchise yet, outside of echos. That and being a 2018 game with a spirit event ought to strike it off, but for some reason I just can't rule it out completely, and I hate it. Still 90% sure it won't be though.
Golden Sun isn't really in a good position either, but Isaac has a chance with fan demand alone. If the ballot wasn't enough, the build up to Ultimate should be, and the reaction after the trophy reveal would also tip them off. It's just a case on whether they think Isaac matters, right now in Ultimate. I'm sure it's no feathers off their back if he just gets considered for Smash 6, as much as it pains the rest of us x)