Okay, long time Legion fans see if you can spot the original Beast Boy from the Heroes of Lallor (Well, in terms of introduction into the comicverse if not chronologically WITHING that comicverse) Mentalla, a Hawkman, assorted Darkstars, Jonah Hex (probably) and Hal Jordan (Who wasn't dead at this point, but soon would be... foreshadowing perhaps? :)
--And the original Vigilante. That's the guy in the blue shirt with the red kerchief and white hat.
Further down, I think that's Scalphunter, not Arak, Son of Thunder.