While all Sour Piñatas are grumpy, each species has its own bad habits. If you tame a Sour, it will become very helpful, such as by stopping fights or scaring off Sours.
You can tame a sour pinata by meeting its Resident requirements. Once you have tamed it, a totem block is added to your Tower of Sour to scare away all sour pinatas of that particular species. (Totem blocks are also available for purchase at Costolot's General Store). To tame a sour pinata you must first let it run its course in the garden. It will spew up sour candies, pick fights, or eat one of your pinatas. Once it has done that it should perform the task required for residency. Once a Tower of Sour block is added, only non-sour pinata of that species will visit the garden. To attract sour pinata, you need to disable the Tower of Sour block from the menu.