Pumkin Berry
A Pumkin Berry is a type of Berry that thaws out a frozen Pokémon. It can be obtained by using Forage on leaves with a Grass- or Bug-type Pokémon, or as a tier 1 special drop.
Trivia
Before Reforged, Pumkin Berries could also be used to craft Ice Heals. The recipe was removed due to many held items being far too easy to make.