Another way to change your pet is to use the morphing potion.

Where can you find the morphing potion?
At the Kauvara Magic Shop or at auction and trade.

Are there morphing potions for all types of pets?
At the moment Kauvara is rushed off her feet simply keeping up with the demand for all her potions. She will be adding more magical brews shortly, including many morphing potions.

If I give my Neopet a transmogrification potion, will it change its stats?
No, your Neopet will keep all its old stats, and you can still increase them as normal.

When you change a pet using a morphing potion does it change its likes and dislikes to that of the species or does just the picture change?
Its likes and dislikes will stay the same, but it will adopt any natural attributes that the new species has, such as a Scorchio's resistance to fire, or a Skeith's ability to eat anything.

Here are some of the potion you can get.