Here is the full list of all 46 Army of TWO: The Devil's Cartel achievements worth 1,000 gamerscore.
200 targets killed in double Overkill
Buy All Outfits
Buy all Weapons, Tattoos, Masks and Outfits
Perform 10 melee kills on wounded targets
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 the game on Insane
Perform 10 cover to cover transition in a row
Complete Confrontation
Complete the Campaign
Buy All Guns
Perform 50 Backstabs
Headshot a target while blind firing
Level up to Rank 25
Complete Assault
200 targets killed in single Overkill (Triggered by your partner)
100 targets killed using either an MMG or an MGL
200 targets killed in single Overkill (Triggered by you)
Complete Rally Point
Complete Outside Contact
Complete Last Resort
Complete Salvation
Complete Enemy Territory
Complete Narco Hell
Level up to Rank 15
Fully customize a weapon with 6 customizable parts or more
500 targets killed while in cover
Destroyed 500 objects
Perform 250 Flank, Surprise and/or Tag Team kills
You took the Aggro for 100 Flank kills
Kill 10 Brutes in Physical Confrontation
Kill 3 targets with 1 grenade
Perform 100 Headshots
Perform 100 melee kills
Perform a x10 Co-op Combo
Destroy 50 cars
Perform a melee kill while you're in Overkill
Level up to Rank 5
Complete Cause and Effect
Complete a mission (excluding New Blood) with a human partner
Perform 50 Hat Shots
Kill 3 targets or more using an explosive object in any level
Players simultaneously killed 2 unaware targets
Make your first kill as a rookie (in Cause and Effect mission)
Complete New Blood