DJ Hero 2

I found this simple to do on the second checkpoint battle in empire mode.

Its in London and against DJ Kid Itch.

I put it on medium difficulty (you can put it on any as far as I know, beginner and easy are too depressing for me) and I still lost two checkpoints and got this.

I lost checkpoints because at the freestyle sections (red button and crossfade) if you are not first to hit the red button or crossfade the other player will get the freestyle part and add to their checkpoint percentage and yours will be considerably lower.

Still, its simple so you shouldn't have any problems.

This achievement is from winning a Battle by earning enough checkpoints to win before the song is even over. You are only able to lose 1 or 2 checkpoints in the beginning before they'll be too evenly split. The later songs have a little more leeway, but not much.