I will tell you what i believe is the easiest way to get this achievement with a boosting partner.
Both of the players have to go on online, choose the same server, and pick a lobby that has no players in it (since its a game from 2010, you will have no problem finding this).
Once you are both in the same lobby, one of the players creates a match room, choosing ranked match and then the other one joins it (other settings for match are not important).
Choose any teams, and let one player score three own goals. The game will end with a forfeit win to the other player. Rinse and repeat 15 times (or 20 if you want to be sure :) ), but keep in mind that once you have 15 matches won (which is 75% of 20 matches won) , you have to win one game by normal result (not forfeiting it). So setup a game with 5 minutes, and you will do it in no time.
Just do it again but change who is forfeiting for your boosting partner to get it.
This goes great in combination with Winning Streak(Online) achievement (you will get it if you go for this one, as soon as you finish with a normal win)