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