Unlock Original Ao2 Weapons
AS-KRI and S0-Z Grand Pinger: Have a save file from the first
Army of Two game on your system and use the same profile as the save.
Unlock Big Head Mode and Infinite Ammo
Big Heads Cheat Code: Complete the campaign on Casual difficulty
Infinite Ammo Cheat Code: Complete the campaign on Casual difficulty
Not What I Thought It Was (5 points): Complete Chapter 1 on Any Difficulty Level.
A Steep Descent (10 points): Complete Chapter 2 on Any Difficulty Level.
A Decent Animal (15 points): Complete Chapter 3 on Any Difficulty Level.
Emergency Room (20 points): Complete Chapter 4 on Any Difficulty Level.
Gone Shopping (25 points): Complete Chapter 5 on Any Difficulty Level.
Survivor? (30 points): Complete the Game on Any Difficulty Level.
Softcore (50 points): Complete Half the Game on Contractor Difficulty.
Hardcore (100 points): Complete the Game on Contractor Difficulty.
Meat Bag (15 points): Use 15 enemies as human shields.
Chaaaaarge! (15 points): Charge through 20 enemies.
The Beast (50 points): Kill 6,666 people in Campaign.
Grenadier (10 points): Kill 3 or more enemies with a single grenade.
Pistolier (20 points): Kill 150 enemies with a pistol.
Old Faithful (20 points): Kill 400 enemies with assault rifles, sub machineguns or shotguns.
One Shot, One Kill (20 points): Kill 100 enemies with a sniper rifle.
Quick Draw (15 points): Kill 25 enemies with a quick draw from mock surrender.
Open Hand Slap! (15 points): Kill 50 enemies with a melee or bayonet.
Unbreakable (25 points): You must survive an entire level in one session without being downed on normal difficulty or above.
Not So Bad After All (10 points): Tie up 15 enemy combatants instead of executing them.
Healer (10 points): Heal your partner 10 times.
Co-Op Sniper (10 points): Co-Op Snipe 5 enemies.
Attention Grabber (10 points): Allow your partner to snipe 5 guys while in Mock Surrender.
In Synch (10 points): Kill two enemies with simultaneous Quick Draws while in Co-op Mock Surrender.
Pumpkin Patch (10 points): Shoot 2 enemies in the head with a single bullet.
Total FistBump Destruction (10 points): Finish the game as best friends.
Total Fistbump Deflation (10 points): Finish the game in a fractured friendship.
The Truth Is Right Here (20 points): Listen to all of the Radio Broadcasts.
Loot and Pillage (20 points): Collect $1,000,000.
Full Arsenal (30 points): Collect All Weapons and Weapon Parts.
Touch Not a Cat but a Glove (50 points): Shoot all Maneki Neko cats in the game.
Hate Monger (10 points): Customize a weapon to high aggro.
The Optimist (5 points): Make a positive coop morality choice.
The Pessimist (5 points): Make a negative coop morality choice.
Humanist (30 points): Save every hostage.
Rock, Paper, Scissors (5 points): Beat your partner at rock, paper, scissors three times in a row.
Fancy Meeting You Here (5 points): Versus: Invite a friend before joining a lobby to play a public match.
Job Seeker (10 points): Versus: In public matches, Kill a player with the primary or secondary weapon from every weapon kit.
DIY PMC (10 points): Versus: Create a custom facemask online (www.armyoftwo.com) and wear it in a public match.
Death Dealer (10 points): Versus: Kill 10 players with headshots on a single map in a public match.
Power Couple (15 points): Versus: Earn the highest partnership score in a Co-op Deathmatch, Control or Warzone public match.
Future Visions (30 points): Unlock all Potential Futures.
All Guns Blazing (30 points): Versus: Kill a player with every weapon, including special weapons, in public matches.
Bound For Life (30 points): Versus: In a public match, survive an Extraction map without suffering a single death on your team.
Survival of the Fittest (50 points): Versus: Complete all 16 rounds of an Extraction game in a public match.
Big Game Hunting (5 points): Versus: Kill both members of a single partnership during a public match.
Fresh Meat (5 points): Versus: Revive your partner and perform a partner reload during the same public match.
Scavenger (15 points): Build a gun using 3 homebrew parts.
Heartless (20 points): Make only negative choices.
Purist (20 points): Make only positive choices.
King of the Hill (30 points): Versus: Win a public match on every map in Co-op Deathmatch, Control and Warzone.
Unlockable Costumes
Beat-Up (end game armor): Complete game once
Civilian Clothes (no armor): Complete game once
Light Armor: Complete game once
Mall Clothes (bare armor): Complete game once
Medium Armor: Complete game once
Oldschool Armor (original Army of Two armor): Complete game once

Achievement Hints
Hate Monger, Scavenger: Both these achievements require some weapon customization and unlocked parts to get. Hate Monger requires upgrading a weapon to have a very high aggro rating; it doesn't require it to be %100 full, but nearly. The style upgrades such as jigsaw and pimp will add a lot of aggro. Scavenger requires the purchase and addition of any 3 homebrew upgrades to your weapon. Items like the Rusty Stock, Metal Plate, and Soda Can Silencer are perfect for this.
Pumpkin Patch: Getting two headshots with a single bullet can be a tough challenge, unless the targets aren't moving. At the start of chapter 3 you can take the General hostage at which point the three other soldiers will surrender. At this point just line up a double headshot on two surrendered soldiers for the achievement/trophy.
Rock, Paper, Scissors: This achievement/trophy just requires you to win 3 games of rock paper scissors in a row. Press Y while not in combat next to your partner to play rock paper scissor and use the d-pad to pick rock,paper, or scissors. This is easily done with another player as you can just have them let you win 3 times in a row.
Grenadier: The easiest way to do this is to go to campaign mode and start up Chapter 5, A Trip to the Mall. At the very beginning of the stage is a hostage situation where 3 enemies gather around a civilian. Put your morality aside and chuck a grenade at the civilian and it should kill him and all 3 enemies, netting you the achievement/trophy.