Zinc

A Zinc is a type of medicine that adds 10 Special Defense EVs to a Pokémon if possible. It also raises a Pokémon's happiness by 5, 3, or 2 depending on how much happiness the Pokémon initially has.

It can be obtained as a tier 2 special drop. It can also be crafted in an Infuser with 10 Apicot Berries and a Clever Feather.