Purdy is part of the Kitties Moshling set. To attract Moshlings you need to plant three seeds in your garden. You buy seeds from the stand on Main Street or at the Port. Each Moshling has a different...
Even if you're not a member you can still get purdy. all you need is any 2 dragon fruits and any moon orchid. You can get them at the moshling seeds shop in between Yukea and the Gross-ery Store.