Once you have spoken to the pink host (some say he's purple, but whatever) in the Toy Box Hub and unlocked Main Street, head into Flynn's arcade on the left hand side.
Walk up to any of the arcade machines and hit
to start searching. It takes a while, as you have to wait for three other players to join.
Once the match is over, and as long as all other players remain in the party, hit
for a rematch.
Only matches with four players count for this, so if one person leaves before you rematch, it will not count.
Complete 10 matches (no need to win) in this manner to get the trophy.