Rare Candy

Rare Candies are a type of item found in Pokémon GO. These items can be converted into Candy for any specific kind of Pokémon. Unlike most items, Rare Candy and Rare Candy XL cannot be obtained via PokéStops. Instead, it can be rewarded through Research, Trainer Battles, and most notably Raid Battles.

To see currently owned revives player can check them out on the item bag page

In-game description
''The Rare Candy can transform into Candy for any Pokémon. For example: when used on a Pikachu, one Rare Candy turns into one Pikachu Candy.''

Trivia

 * Rare Candy was introduced in version 0.67.1 and Rare Candy XL was introduced in GO Beyond (along with regular XL Candy).