A candy that is packed with energy. It raises the level of a single Pokémon by one.
While holding a Rare Candy in your hand, Pokémon will follow you around. Right click on a Pokémon to give it the Rare Candy.
TIP: Try to find a pokecenter that you won't be living in/healing your pixelmon in, etc... Then take the glowstone dust from there so you don't have to go to the Nether.