If you want to catch a pinata in a trap, you'll need to lure it in with some bait. When you are in the Pinarctic or Dessert Desert regions, press to bring up the menu, and point at the Bait Bag using the . Now press to open the Bait Bag in the region. You can cycle through the available bait by using the left and right bumpers. When you have found your ideal bait, drop it into position using .