WWE 12

This is pretty straight forward, but just in case somebody can't figure out how to select a created arena - when you set up your exhibition match and it shows the hype graphic of the two (or however many) wrestlers on the screen, go to 'Select Arena' along the bottom, and you'll see a grid showing all the built-in arenas. At the bottom of the screen will be an option for created arenas. Select that, and then your arena. Once the match starts, you'll have the achievement.

Create an arena and set up an match. Click on 'select arena' and press RB to find all of your custom arenas. As soon as you press 'play match', the achievement will unlock.