Just out of curiosity, why is Incineroar the character people are most confident in? Verge said that neither of his two main sources heard about Incineroar, and that the SE rep was basically guaranteed.
I mean, I don't disagree that a Pokemon rep is more likely, but I would've assumed that practically everyone on Smashboards would've clinged to Geno/SE rep being that last newcomer.
My theory on that goes on this thinking:
1) He usually picks a starter; with only Jigglypuff, Mewtwo, and Lucario falling outside that (and when Trainer was gone, Charizard was kept solo)
2) The Pokemon Choice tends to be the one promoted more (Lucario had is own movie at the time; this time concept art had Ash with Incineroar)
3) Decidueye is already in Pokken Tournament*
*I know this is blasphemy to say, but I don't think Sakurai would use a character already being used in another Switch fighting game. How much hype could honestly be generated with the reveal of "Here's a new pokemon! And he's already in another fighting game that isn't that old yet,
Decidueye Soars in!
I mean, yeah, he's not impossible, but #2 does seem to weigh prominently. Mewtwo is still one of people's favorite Pokemon; Pikachu is the mascot of the series, Charizard is the most well-recognized Pokemon out of the 800+ there are, Greninja was so pushed int he anime, he got his own form for being so bonded to Ash (sorry Pikachu, you're not close enough to Ash, I guess), Lucario had his own Movie at the time and was pushed a bit as well. Jigglypuff is kind of the outlier. At the time of 64, she was constantly following in the anime and causing havoc when using 'Sing', so I honestly think she was included as a bit of a 'Joke' character, then kept because she was part of the original cast.
DISCLAIMER: I know there's no set theory or anything written in stone for how Sakurai chooses a Pokemon rep (or any rep for that matter), but so far, for the Pokemon reps and 4 Games each introducing a new Pokemon character, he has yet to not pick a Pokemon who's pushed strongly by the Pokemon company. And at the time of his choosing, he would have had access to concept art which would show not only who the anime would end up pushing (since it was the only one of the concept arts that even showed anime character), but what type of fighter Sakurai could make him:
In the end, I would love for it to be an Ultra beast, Necrozma, or even Tapu Koko (since the games revolved around them and the anime has had arcs around them), but as far as Incineroar himself goes, I really believe he has the best chance out of the Gen 7 starters.