If you are having trouble with this, simply get a friend, start a private match, and idle your way to wins.
Press X to start, and don't do anything else. Stay in the character select screen. Let the timer run out, it ends in a tie, and you both get a win.
- This cuts the time in half for two people to easily get the achievement, so it should take ~50 minutes total, or 5 matches, for both people to get 5 wins, with no effort required.