At this point in the game's lifespan the multiplayer scene is pretty dead, and those who do play are incredibly OP guys. So if you would like to increase your chances of getting this, get together a boosting session or some friends, at least 4 including yourself, and search at same time the quickmatch FFA and hope you get matched up, if not quit out and try again. Once you do just have 1 person at a time power up and kill everyone else with a super at same time. Depending if its a time or stock match you may have to research for other people in the party. This can also work for Victorious, This is Living, Triple Kill, and Team sweeper in 2v2 mode.
If you disagree with this Solution Please leave a comment as to why before Down voting and ill do my best to fix. There is no spoilers within this solution.