Instructions
Access the menu by pressing "X" at any time during game play, then use the left analog stick to select the petal in the top-left -- at the 10 o'clock position. This is the "Tower of Sour" option, which is disabled by default. Press "A" to enable it. The Tower of Sour prevents Sour Pinatas from invading your garden.
Level up as usual, which is contingent on developing a well-kept garden with lots of plant and Pinata variety. Sour Pinatas are much more likely to invade an appropriately leveled and thriving garden with happy Pinatas, since their main goal is to disrupt a Pinata garden.
Use the correct strategy on the Sour Pinata, based on the type of Pinata it is. For example, the Mallowolf can be placated and tamed by feeding it a Pigxie. A Crowla can be lured in by the presence of a birdbath, then fed Medicine in order to tame it. Consult the Sour Pinata Guide, which advises players on how to identify and tame the Sour Pinatas.