This video shows the achievement unlock. To unlock the "Matchmaker" achievement you need to win in 20 match variations. There are 38 different match option between one-on-one, two-on-two, handicap, fatal 4-way, triple threat, & 6-man. Just go to the play menu & chose between 12 options in one-on-one, 6 in two-on-two, 2 in handicap, 7 in fatal 4-way, 7 in triple threat, & 6 in 6-man. Personally I mixed & matched some from each, saving the ironman match for the achievement.