To objective to this achievement is to win three Co-op Matches in a row, which involves fighting AI-controlled enemies easy and brutally difficult.
The way the 3 wins in a row are gotten is that the Ally group plays in three consecutive "rounds" for their streak. The Enemy team will vary from low-level robots to Master Enemy groups such as Super Robots or Ninjas. Make sure your team is well equipped for this, as the Master Enemy groups get real nasty in the difficulty curve.
Once all three "rounds" have been won, all members of the ally team will have the achievement.
NOTE: If you somehow drop out from any of the three rounds either by network issues or intentionally disconnecting, the winning streak will be halted and you will have to start all over again.