It's been confirmed the first 6 characters are the 6 first regulars of the team . I believe since Rocket , Red Arrow and Zatanna have been apart of the team they'll be playable as well. It's coming in 2013 So Blue Beetle and Lagoon Boy could be options. And the 12th could be Wonder Girl. I believe 7 villains could possibly be the light. While the remaining 5 could be Sports Master , Cheshire , Harm , Worton , and Joker.
H1: Robin
H2: Aqualad
H3. Kid Flash
H4: Superboy
H5: Miss Martian
H6: Artemis
H7
H8
H9
H10
H11
H12