Possible 2 in 1 characters...

Seen concerns about Reed being too similar to Ms Marvel. One way to distinguish Reed from Kamala is to pair him with Herbie. Reed's greatest power is his intelligence, how do you show case that in a fighter? Have him team up with one of his inventions. Would make him way more interesting. I hope he's not just Dhalsim from SF

Cloak and Dagger would be really interesting. They could make Daggar the lead character and Cloak would function as the unique attack. Cloak can absorb projectiles and hold them in the void until you the unique attack again and fire it back like Kirby. Also would have teleport, so pretty much Goku Black's special where he would vanish to different spots depending on L, M, or H.

They kinda did Rocket and groot in MvC but this time just have Groot be the lead and rocket rides his back and fires range attacks.