This is really awesome! I'm trying to figure out who all of these characters are. My best guesses are, from left to right:
Killer Croc, Black Mask, Deathstroke, The Ventriloquist, Deadshot, Bane, The Riddler, Poison Ivy, Harley Quinn, The Joker, Two-Face, The Penguin, Catwoman, The Scarecrow, The Mad Hatter, Clayface, Ra's al Ghul, Talia al Ghul?, Great White Shark?, Hush, and Mr. Freeze.