The downfall of this game, from watching those GameTrailers chucklefucks talk about it, will most likely be how it's built around the Final Smash mechanic from Brawl. Final Smash is the grossest example of Nintendo trying to mitigate skill disparity since Mario Kart's blue shell. Parappa has a super that insta-kills everyone. that's like eight blue shells of holy shit this is hot trash.
At the very least I hope they have a mode where you get a different scoring system. Ideally, I would love the smash percentage system, but maybe the developer feels that's too close to Smash and/or they believe their own "it looks similar, but it's actually different" spin.
I hope they include some of the more fun characters and not too much real people nonsense like killzone/resistance/uncharted/whatevz. Loco Roco and Patapon could be swarm-like characters where you had direct control over a small group of loco rocos/patapons and the amount of characters you had could be affected.