You will need at least 3 players for a battle. One person will pull a card. Then both competitors have to pick a song based on that same card and perform. The 3rd player will act as the judge and decide who won that round (based on song selection and overall performance).
If you have more than 3 players that's okay, you just need someone to act as the judge each round. Keep going until each player has battled at least 4 times, and then declare the winner!
If playing with groups, first pick group names just to add to the fun. There should be 2 or more groups battling at a time, and 1 group serving as the judges. One person from the first group will pull a card, and all of the groups have to pick a song based on that same card and perform.
The judges will decide which group won that round (based on song selection and overall performance). Keep going until each group has battled at least 4 times, and then declare a winner!