Here is the full list of all 50 Injustice: Gods Among Us achievements worth 1,000 gamerscore.
Get 100 Stars in S.T.A.R. Lab Mode
Perform every level interaction once
Unlock all costumes in the Archives
Play 200 complete Online Matches
Win 100 complete Online Matches
Complete Battle Mode
Complete All S.T.A.R. Lab Missions with 3 Stars
Beat All S.T.A.R. Lab Missions (Excluding DLC)
Win 10 complete Ranked matches
Reach Level 100
Unlock everything in Archives
Complete Classic Battle with all characters
Enter Online Practice with someone on your friends list
Knock opponent through all transitions across all levels
Perform every special move of every character
Perform every Meter Burn special move of every character
Complete Classic Battle with any character
Vote Correctly in a KOTH match
Defeat a Survivor
Dethrone the King in an online match
Cause maximum damage in all Arenas (does not include Practice mode)
Perform every character's supermove
Perform a 10 hit combo with every character
Defeat every Villain With Batman
Win all story mode minigames
Perform 8 throws and win in a multiplayer match
Use every interactable and win in a multiplayer match
Complete 100% of Story Mode
Complete 50% of Story Mode
Win with Batman using every special move and his Supermove
Send an opponent through all three Metropolis transitions in one fight
Knock an opponent through a transition
Win a match as Deathstroke without missing a shot (minimum 12 shots)
Make a comeback when at low health (10% or less)
Win a Clash sequence with any character
Win a match with Green Arrow using only arrows
Enter Practice Mode
Unlock a costume in the Archives
Reach Level 10
Win 1 complete Ranked match
Win a single online match
Get 3 stars on 1 S.T.A.R. Lab Mission
Complete 1 S.T.A.R. Lab Mission
Equip a new Character Portrait
Equip a new Icon
Equip a new Background Image
View Your Hero Card
Win a match with the super move of any character
Win a multiplayer match with a timeout
Complete Tutorial