Here is the full list of all 46 Army of TWO: The Devil's Cartel achievements worth 1,000 gamerscore.
Apply the maximum number of layers on a customized mask
Create your own Custom Mask
200 targets killed in double Overkill
Buy all Weapons, Tattoos, Masks and Outfits
Buy All Outfits
Kill 3 targets or more using an explosive object in any level
Complete the game on Insane
200 targets killed in single Overkill (Triggered by your partner)
Level up to Rank 25
Buy All Guns
You didn’t go wounded once in a mission (medium, hard or insane)
Perform a x10 Co-op Combo
Kill 10 Brutes in Physical Confrontation
Perform 10 melee kills on wounded targets
Complete the Campaign
Complete Confrontation
Perform 50 Backstabs
100 targets killed using either an MMG or an MGL
Complete Assault
Perform 100 melee kills
Complete Narco Hell
Complete Enemy Territory
200 targets killed in single Overkill (Triggered by you)
Complete Salvation
Level up to Rank 15
You took the Aggro for 100 Flank kills
Kill 3 targets with 1 grenade
Perform a melee kill while you're in Overkill
500 targets killed while in cover
Complete Last Resort
Complete Outside Contact
Destroyed 500 objects
Perform 250 Flank, Surprise and/or Tag Team kills
Players simultaneously killed 2 unaware targets
Complete Rally Point
Destroy 50 cars
Perform 100 Headshots
Perform 10 cover to cover transition in a row
Complete Cause and Effect
Complete a mission (excluding New Blood) with a human partner
Fully customize a weapon with 6 customizable parts or more
Level up to Rank 5
Perform 50 Hat Shots
Headshot a target while blind firing
Make your first kill as a rookie (in Cause and Effect mission)
Complete New Blood