The Question: proberly wont be, but can still hope coz he is cool
Green Lantern: He's a big hiting space hero, he will be in this and wearing some kind of amour like costume
The Creeper: good guy joker, can't see why he couldn't be in the game
Green Arrow: seeing as he is getting a TV show, i wouldn't see why DC would leave him out of the game
Nightwing/robin: i'm guessing it would be Nightwing or Robin, seeing as Robin was in arkham city and was pretty good playable character, i cant see why they would leave batmans male side kick out of the game
Batgirl: She hasn't been in a game yet, but i dought they will put 3 bat like people in game.
Deathstroke He will more then likey be in the game, seeing as he is the next biggest ninja when put next to batman
Manchester Black: i like this character....badass telepath from the elite, he won't be in the game but i can hope because of the recent Superman vs the Elite cartoon film mo bob
Cheetah: Wonder womans main foe, i only know this from that from Justice League: Doom
Joker: he will be in the game, one of DC's biggest villains and i see no reason why, as he had the best joke in all of MKvs DC
Lex Luther: If super mans in a game, Lex will be in, in his big ass anit-superman suit
Mirror Master: i think he is a cool villain, powers could mix well in a fighting game with mirror based tricks
Mr.freeze/captain cold: The ice in the trailer means its either of these two, as the ice was aimmed at Flash proberly captain cold, but in the trailer harley was fighting Wonder woman so could be Mr.Freeze.
Deadshot: Popular villian, and i don't think really done justice in Arkham City, so it would be cool seeing him in a game
Bane: Smart big guy would be cool in game, with or with out venom, would be cool seeing if they just did brutish bane or smart bane seeing as he is main villain in newest batman film he is likely to be in this game
Red Hood: would add a lot more backstory for batman and some emotional character interaction
Lobo: Why cant the big alien 'main man' be in the game, the pale alien i think would make a good addition to the game.
Catwoman: She was in MK vs DC, a popular character will proberly be in the game anyway.