Here is the full list of all 51 Monday Night Combat achievements.
Achieved a 3 kill streak in a Crossfire match
Cool guys don't look at explosions
Attach an Assault Bomb to an enemy Pro
Finish Tutorial
Completed "Exhibition" Blitz Mode
Achieved 15 kills in a Crossfire match
Completed "Season" Blitz Mode
Completed "Playoff" Blitz Mode
Achieved a Ring Out during a Crossfire match
Achieved 10 grapple kills in a Crossfire match
Achieved a pancake on an opposing player using the Gunner's Ground Slam ability
Achieved "Most Valuable Player" in a Crossfire match
Completed "The Scramble" Blitz Mode
Achieved a kill on an opposing player while they were upgrading skills in a Crossfire match
Achieved a Triple Kill
Attach a Support Air Strike Beacon to an enemy Pro
Score a 6 Kill Multikill
Score a 25 Kill Streak
Score 2500 Kills with Assault's Rifle
Score 2500 Kills with Support's Heal/Hurt Gun
Score 2500 Kills with the Gunner's Minigun or Dual Minigun
Score 2500 Kills with the Tank's Jet Gun
Score 2500 Kills with the Sniper Rifle
Score 2500 Kills with the Assassin's Dagger or Sword
Collect 100 Bacon Pickups
Receive over $9000 in lifetime earnings after a Crossfire Match
Score the most kills in a single Crossfire Match
Score the most assists in a single Crossfire Match
Score 2 Jackbot Kills in a single Crossfire Match
Score a Kill with a melee attack
Score a Kill with the Jet Gun's alternate fire spin while juiced
Pickup a total of 100 prizes in one match
Use Juice 7 times in one match
Score 150 Ringouts
Score 150 Ejector Kills
Build or Upgrade a Lazer Blazer Turret 500 times
Build or Upgrade a RockIt Turret 500 times
Build or Upgrade a Shave Ice Turret 500 times
Destroy 2500 Lazer Blazer Turrets
Destroy 2500 RockIt Turrets
Destroy 2500 Long Shot Turrets
Destroy 2500 Shave Ice Turrets
Score 100,000 Kills on Slim Bots
Score 100,000 Kills on Black Jacks
Score 100,000 Kills on Buzzers
Score 2500 Kills on Bouncers
Score 2500 Kills on Scramblers
Score 100,000 Kills on Gremlins
Score 2500 Kills on Gap Shots
Score 1000 Kills on Jackbot XLs
Score 30 Kills in a Crossfire Match