I want to turn my common Jollin into a Nostalgic Jollin. I'm not sure if it takes a magic potion/quest/something else. Please let me know if you know how to. :)

You'll need to get some and take them to Vanya. Then you'll do a little quest for him and he'll turn the instructions into a toy. Then you take the toy and an back to him and he'll change your active pet.

Thank you so much!