Both games are in very good condition. Zumba Party does have some light scratches on the playing surface, but they do not impact playback. Zumba Core's disc is in mint condition. 

As you can see from the photograph of the instruction manual, you do not need the belt to play these games. It is just a device that allows you to play the games hands-free. You can get the same effect using a running belt, or any other device that allows you to secure the Wii remote at waist level.