Get A Kong Buddy Without Purchasing It From Funky Kong's Shop:

This requires two controllers. Simply add a second player from the World Menu before you start a level. Press Start, then select Add/Drop. Press A on the second controller. Then choose your control options. Finally, select between Diddy Kong, Dixie Kong, or Cranky Kong. From here, you can play with a second player, or remove the controller from the Add/Drop menu. You will still have your Kong Buddy.