Easiest way I got "THIS" achievement was like this.
I went to game options, set Games per match: to 1 of 1,
Points per game: to 7
Started an exhibition match on EASY... then I picked my favorite character (Jesper) against someone I hated (Kumi). Each game should take less than 2-3 mins to complete. After each game, I kept hitting rematch and got to 20 wins in no time. Have fun...