MultiVersus

Easiest done with a boosting partner as its hard to guarantee a low damage ringout otherwise.
Find another player by asking a friend, using Xbox LFG, or creating a TA session. This should take no longer than 15 minutes to get for both players. Should take less.

Create a custom lobby, set to 1v1, kills to win 4, timer 3 minutes.
Have your partner stand on the ledge, hit him once to smack him off. Do this 3 times, have your partner do it to you 4 times to win the game. Rematch. Now they get 3 and you get 4. Now one more rematch and you each get 3 and the achievement should pop.

I have no consistent solo method.