Team Kopanito
Play a tournament match with a friend

This achievement will require a controller. I used my steam controller and my keyboard to play as two players. I idled the keyboard player while playing with the 2nd player with my controller. Here is a step by step on how to gaining this achievement.

1. From the main menu go to Play Offline and then Custom Tournament
2. The type of tournament doesnt matter choose any of the three available.
3. The settings do not really matter though to ensure a quick victory I changed the difficulty to beginner and the time to 2 minutes.
4. Press Start and then play.
5. Use your controller for Player 1 and hit space to join with your keyboard as Player 2 (or vice versa)
6. Move both players to the same team not sure if this matters but just to be safe.
7. Then Start the game.
8. Play with one player while idling with the other.
9. Once the game is over and you exit the game you will get the achievement. I do not believe you have to win but to be safe I did.