From Niantic's blog post:
"A Rare Candy is a mysterious candy that, when used on a Pokémon, turns into that Pokémon’s Candy. Golden Razz Berries will greatly increase your chances of catching a Pokémon you encounter in the wild and can also be given to a Pokémon assigned to a Gym to fully recover its motivation meter. Technical Machines are items you can use to permanently teach a Pokémon a new Fast Attack or Charged Attack."