Definitely could benefit by adding animalistic characters such as Grodd, and Cheetah into the roster, since even though most of the rosters will be made of humanoid chaaracters, a slight change will be a breath of fresh air. And Gorilla Grodd can be a perfect character to use against other players for his super, which involves him using his mind-controlling helmet or telekinesis to make the players' control be either disoriented or completely stunned until either attacked or a few seconds are up.
I kinda agree with OGoddess that since the roster numbers are between 24-27 characters, they need to add more females into it.
I still thinking that Hawkgirl (Hawkwoman), Black Canary, Raven, Huntress, Killer Frost, and Circe will possibly make it to the roster.