Instructions
Press "F2" on your keyboard to open the village menu in your "Viva Piñata" game. On the Xbox 360, press "X" and use your left analog stick to select the village from the flower-shaped radial menu.
Use your mouse or left analog stick to select the Miss Petula's Paper Pets shop in the village menu. Select the Ponocky from the list of domestic piñatas offered in the shop. The Ponocky costs 2310 chocolate coins and requires the purchaser to be at least a level 20 gardener.
Select an area in your garden with your mouse or left analog stick and left-click or press "A" to place your Ponocky. You can purchase additional Ponockies using the same method, provided you have sufficient chocolate coins. When you have acquired multiple Ponockies, you can romance them to produce additional Ponockies for your garden. The romance requirements for Ponockies are one tail bow, one piece of carrot cake, ten flowers, 300 square Pinometers of grass and a Ponocky house in the garden.