There are two ways you can get this achievement:
1. Second Controller. You can hook up a second controller and win 50 games. The easiest method is to play 3-ball or have the one controller sink the black ball early to lose to your gamer profile controller.
2. If you don't have a second controller or you enjoy pool you can play against a computer. Set the computer to a "One Star" rating and also set in the options for you to have a three point aiming. Play the heck out of 3-ball.