Batman = Owlman, Nite Owl
Superman = Bizarro, Cyborg Superman, Ultraman
Wonder Woman = Artemis, Superwoman (from the Crime Syndicate)
Supergirl = Power Girl is enough, and I can't think of any premier skins, though I would like her to have a Red Lantern shader similar to how Green Lantern's shaders work with his costume.
Aquaman = Ocean Master, Justice League movie (Jason Momoa)
Atrocitus = I can't think of anyone that could work
Gorilla Grodd = Ultra-Humanite (if he has telekinesis which I thought he did)
Deadshot = I can't think of anyone that could work here either
Harley Quinn = I just hope she has Yo-Yo gear that could be used
Flash = Wally West, Zoom, Johnny Quick
Blue Beetle = man, I'm drawing more blanks then I realized I would
Bane = *sigh* help me out here
Poison Ivy = do you think they could do a Killer Frost and recreate the super and animations to look icy? They changed the color of GL's supers based on his ring power so maybe?
Brainiac = nothing
Robin = Katana (that would work right?)
Black Canary = nadda
Swamp Thing = zip
Catwoman = zero
Cheetah = already has one and that would have been my best guess
Cyborg = his Grid premier skin was the reason I want the other Earth 3 characters
Doctor Fate = nothing
Green Lantern = Sinestro (hope the rumor is true), Star Sapphire, Saint Walker, Guy Gardner
Firestorm = ....
Green Arrow = Arsenal
Black Adam = Shazam
Captain Cold = his is good enough
Scarecrow = doesn't need one
Darkseid = also doesn't need one
Joker = there's no one like Joker
Red Hood = Flashpoint Batman (cause of the guns), and, wishful thinking just for funsies, John Wick lol
Starfire = Blackfire
Sub-Zero = ???