Boon confirmed that there are will be at least 100 costumes( He didn't say that they were all on disc). Lets work together to unlock them!

24 Characters 22 Modes to possibly unlock a costume. I believe that beating each mode with a certain character will unlock a costume. If we work together we can discover how to unlock each costume faster.

Costumes unlocked in Game( Not IOS)

Boss Grundy – Complete Classic Battle Mode with any character
Godfall Superman – Complete Story Mode with any character
Lex Luthor Kryptinite – Complete S.T.A.R. Labs with at least one star
New 52 Flash – Create a WB ID, or login to your WB account
Elseworld Flash - Get 3 Stars on all missions in STAR Labs
Yellow Lantern Alternate – Win a ranked online match
New 52 NighWing -- Reach Level 30
New 52 Shazam -- Complete all Shazam S.T.A.R. Lab Missions

Story Mode -- Reward Godfall Superman

S.T.A.R. L.ab Unlocks
Lex Luthor Kryptinite – Complete S.T.A.R. Labs with at least one star
Elseworld Flash -- Get 3 Stars on all missions in STAR Labs
New 52 Shazam -- Complete all Shazam S.T.A.R. Lab Missions

Unlockable Battles in Battle Mode

Classic Battle -- Win with anyone to get Reward is Boss Grundy
Hero's Only -- Reward ?????? No Reward with;
Villains Only -- Reward ?????? No Reward with;
Poisoned -- Reward ?????? No Reward with;
Survivor -- Reward ?????? No Reward with;
Combo Heaven – Reward ?????? No Reward with;
Countdown – Reward ?????? No Reward with;
Full House – Reward ?????? No Reward with;
Fully Charged – Reward ?????? No Reward with; Shazam
Give and Take – Reward ?????? No Reward with;
Help From Above – Reward ?????? No Reward with;
Impossible – Reward ?????? No Reward with;
Injured – Reward ?????? No Reward with;
Mirror Match – Reward ?????? No Reward with;
Mystery – Reward ?????? No Reward with;
Sidekick – Reward ?????? No Reward with;
Speed Run – Reward New 52 Flash No Reward with; everyone else
The Max – Reward ?????? (Rumored NEW 52 Green Arrow) No Reward with;
Unstoppable – Reward ?????? No Reward with;

Post what modes you have beat with each character. This way we can cross off characters for each mode.

No need to post who you beat Classic Battle with.
Since I'm deployed and can't play the game :( I'll keep this post updated when I don't have a mission.
I'll keep this post updated.