I hope when they do the multiple versions of Green Lanterns, I hope they have their own unique movesets that will somewhat set each other apart and not just some costume swap, even though I doubt they can do it.
Characters who no doubtly be on the roster.
Villains:
Deathstroke
Joker
Mr. Freeze
Lex Luthor
Cheetah
Darkseid
Sinestro
Black Manta
Vandal Savage
Killer Frost
Black Adam
Heroes:
Martian Manhunter
Aquaman
Hawkman or Hawkwoman
Nightwing
Green Arrow
Black Canary
Green Lantern (question is: Which one?)
Captain Marvel