Also if you do decide to add skins, the prisoner from BattleBlockTheater could simply have the different skins be the different head shapes. (If deciding to add them) (Their secondary attack could also be like Ena's where the directional key uses one of the different tools from the game like the mine and the boomerang, etc. They have a punch and an uppercut move already so yeah. That's why I believe they are a perfect fit.)
Longer adventure mode(which is probably already planned) or specific character story playthroughs.
Starfish(Charlie The Unicorn) assist trophy. Or Lulz and Rofflez(The Blue and Pink Unicorn).
Whale Assist?(BattleBlockTheater)
Also Otis(Pico's cousin) as an unlockable perhaps?
A four player mode, competitive (two teams, how many each team can knock out. if not four players then just two but same concept)
And ya prolly already saw this coming but vs?
I know this is quite a lot to request out of nowhere so honestly I don't expect any of these to actually be added but it sure would be nice at some point.
Maybe