Nectar

Nectar (Japanese: ミツ Nectar) is a type of item introduced in Generation VII that allows to change forms.

In the anime
Yellow Nectar appeared in A Seasoned Search!. It was one of the ingredients needed to prepare a dish at her family's restaurant, so she and  headed to Melemele Meadow to get it. There, they witnessed a Baile Style sipping it from a flower and changing into Pom-Pom Style Oricorio.

Artwork
These are artwork of the items as seen in the Pokémon Global Link.

In other languages
Nektare Nettare ミツ 花蜜