Tag Duel wins and Single Mode wins BOTH count towards this achievement. Every single duel you win counts towards this achievement. I will explain the fastest method for boosting this achievement:
First, you should create a Player Match with the settings: Game Format: Single, Amount of Time: 30 seconds. The rest of the options don't matter. Once you create the match, invite your boosting partner. Now, start the game. The person who will be losing the duel should choose Paper and the person who will be winning the duel should choose Rock in Rock, Paper, Scissors. Now, the losing player should just wait out their turn until time runs out. The other player will get the win. I suggest doing this in intervals on 10 because it seems to go by faster.