This achievement will require two people total, and must be done in Dance Battle. There are normally two or three Free-4-All's per song, and there are four columns of moves. Despite it looking like you have two columns of moves and your opponent has two, you can nail moves in any of the four columns. The various moves employed throughout the song will be scattered in the four columns, one after another. Nailing a move will add 10,000 points. Nailing a move with a gold flashcard will add 40,000 points. Naturally your best bet is to nail as many gold moves as possible. You should easily be able to get three before the Free-4-All ends. Just ask your competitor to sit back and let you get the points.