Shade because his shadow based powers are cool.
Ragdoll. He's creepy, weird and can be cool freak character.
Raven. Because Raven.
Creeper because he doesnt gets enough spotlight and could be another cool addition as freak.
Jonah Hex. Loved Erron Black in MKX so I hope more cowboy like characters make it cut.
Cassandra Cain, because I take her over Barbara any day of the week, and she's also one of the coolest characters in bat family.
Vixen if done right could be cool and not overused character from DC
We already had Killer Frost how about we got Livewire this time?