You can tame a sour piñata by meeting its Resident requirements. After it is tamed, it goes into a Cocoon, after which it turns into a wild piñata which immediately becomes a resident piñata of your garden. Once you have tamed it, a totem block is added to your Tower of Sour to scare away all sour piñatas of that particular species. (Totem blocks are also available for purchase at Costolot's General Store). To tame a sour piñata you must first let it run its course in the garden. It will spew up sour candies, pick fights, or eat one of your piñatas. Once it has done that it should perform the task required for residency. Once a Tower of Sour block is added, only non-sour piñata of that species will visit the garden. To attract sour piñata of a wanted species, you need to disable the Tower of Sour block for that species from the menu.