Army of Two (EU)

Requires SSC Pack (600mp from marketplace)

Simply set the game up ranked match SSC Challenge (this can be done with four friends just invite them at the set up screen.) Choose a map I found warehouse 1 to be quickest. The first team to the end wins set it to 3 rounds and win all 3 rounds and "Achievement Unlocked."

Same as detailed here by Elite Hero (I found Warehouse 2 even quicker), but a note I would like to make that I noticed when I did this achievement. You can win a round by just scoring more points/progressing further than the other team, but for the achievement to unlock you will actually need to get to the end of each round.

(I can only confirm this is how I had to get it, my apologies if my game just glitched on me the first time)