Give all to another and save yourself
Roster might look like thisThat's my biggest fear about a crossover game, the roster would need to be enormous, otherwise it would legit just be like half the JL vs half the Avengers, with no room for the loveable jobbers and side characters. Like, take the Injustice 2 roster and try to replace half of the characters we got with Marvel characters and see how many notable characters you're able to represent from both universes.
DC Mainstays (guaranteed): Batman, Superman, Wonderwoman, Harley Quinn, Catwoman, Green Arrow, Flash, Cyborg, Aquaman, Green Lantern
Marvel MCU (Gauranteed): Iron Man, Cap, Hulk, Thor, Black Widow, Scarlet Witch, Captain Marvel, Falcon
DC 2nd Tier (solid choices to make it): Joker, Supergirl/Powergirl, Scarecrow, Darkseid/Doomsday, Teen Titan Rep
Marvel 2nd Tier (solid choices to make it): Panther, Guardians Rep, AntMan/Wasp, Loki, Thanos, Winter Soldier, War Machine
DC Fan Favs (not everyone gets in): More Titans, Batgirl, Ivy, Hawkgirl, Grodd, Swamp Thing, Mera, Circe, Zod, Nightwing?
Marvel Fan Favs (not everyone gets in): Xmen, Spiderman + Spiderverse, F4, more villains