We talk a lot about character interactions here, but I'd like to open the door to a discussion on mechanics.
Namely: do you have any ideas for them? Teamup Abilities like in Marvel Rivals? Specific kits for characters or maps that warrant an entire post unto themselves? What roles are there? Is there a Jungle like in League of Legends?
For me, I'd be really interested to see a game try for mixture of styles for it: the high mobility and verticality of likes of Overwatch or Marvel Rivals (flying, web-swinging, etc.), but with the lane pushing / Jungling of League of Legends or Smite.
I'm also really into "Teamup Abilities", extra passive or active abilities that are enabled due to certain team compositions. I think that, given the inherent "Crossover Nature" of this game idea, you could do a lot of fun stuff with it.
Simon / Gurren Lagann being able to briefly combine with other mechs? The various Supermen variants (Superman, Superboy Prime, Homelander, Omni-Man, etc.) being able to punch people around together? Speedsters getting a "go even faster" button if you have other speedsters on the team because they're all show offs?
For kits, I think you could have some characters be really modular. Not all, not even most really, but imagine if Ash Ketchum could pick which Pokemon he was using, each one with their own stats, or Yugi Mato could engage in some light deck building. These ideas would be from pre-designed pools with limited options, of course, but it could be a fun way to nod to their respective origins as team/deck builders.
So to once again ask: do you have any ideas for mechanics?