Quan Chi as Lex Luthor, Erron Black as Deathstroke, Shinnok as Sinestro, Goro as Bane. And Mileena as Joker with Tanya as Harley Quinn.
Maybe have the Kombat Kids as the Teen Titans? Cassie as Starfire, Jacqui as Raven, Takeda as Cyborg, and Jin as Robin.