3 battles are done and Barry, Jason, plus Joker are already in round 6. So besides Iron Man, Hal J, and Supes, 10 more heroes are still battling in round 5 (assuming it's Last-16). I think Wonder Woman is the only remaining female, and will battle Batman. Thor should still be swinging his hammer as well. Colossus (biggest surprise thus far). Spider-Man.
Maybe Green Arrow (did Ollie win last round?).
One more? Sinestro or Thing perhaps. Who won that match?