Damn, this Papa Genos video is interesting. I don't think he'd say this without a very good reason to believe it. Incineroar being a leak bait character makes total sense if you think about it. People were expecting a Pokemon rep and with how Sakurai picks Pokemon Incineroar seems the most likely, so he's an easy name to bait people with. It'd also explain why Verge's Smash knowledge got so limited the moment that it was said that a source told him Incineroar was in the game. I mean, he was on a roll during E3, but since then he hasn't really said much. It wouldn't surprise me if a lot of these industry people are just brushing this leak off because of no Incineroar, since they're being incredibly vague about, While the video hasn't dropped yet, even Spawn Wave's gripe with the leak seems like it comes down to "Well, the character I heard isn't in it and I trust my source", and even if its Sora at the VGA, it doesn't contradict this leak at all as that would likely be DLC.
Maybe I'm getting too tin foil hat here but Papa Genos isn't Lax Chris. I doubt he'd say something rather big if he didn't trust it.