>>41218100Sweets. Despite being Pokemon they have very developed palletes, and like human Supertasters things that are very sour or bitter are too much for them. They'd really like fruits, berries, or things with flower flavors (like rosewater or lavender.)
If you're not attentive to their special diets though they're equally happy to have human sugar bomb sweets, so less experienced trainers often wonder why their Gardevoir always want ice cream and cake.
