Hey Gamers! Welcome to NHL THREES in NHL 19!
Video below if you prefer video!
This is a very easy achievement that requires you to win a Threes mode game in online co-op. Once you go into the Three's mode and select the game it will ask you if you want to play offline or online coop. Select Online coop.
Even though couch coop option shows up as an option, you actually MUST unlock this achievement via an online partner. Once your players are ready you can select your difficulty, selecting rookie or semi-pro makes this achievement a breeze. You can also elect for shorter games by selecting a low goal limit with the money puck on!
Hope this is helpful!
-Damron and OmegaD34TH Out