True SSC Challenger Achievement in Army of Two (EU)

Win every stage of a ranked three round SSC Challenge matchThis is unlocked when you and your partner win 18 out of 18 'stages' in a three round SSC challenge. There are 6 stages a round and the end of each stage is marked with a claxon and confetti going off. This could be done legit pretty easily but can also be done at the same time as when your boosting partners are going for the "SSC Challenge Marksman" achievement.