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