What about her?
She IS one of the more famous characters in the Universe of DC...
I mean she one of the oldschool supervillains of batman. She deserves to be a playable character in Injustice...
(Seriously I did not buy myself the game, but if there would be a DLC with her, I would)
she's not actually in it, but in the Arkham Asylum stage there's a bunch of vines and poisonous flowers in one part. Kind of a nod to her i guess
I believe she should be in the game, as she is one of my favorite Batman villians (Along with Scarecrow, Bane, Ra's a'l ghul and Clayface)