Alolan Pokémon now hatch from Eggs that were gifted by another Pokémon GO player, including Alolan Meowth, Alolan Sandshrew and Alolan Vulpix

One new way to interact with your friends in Pokémon GO is by giving Gifts. When you spin a Photo Disc at a PokéStop or Gym, you have a chance of collecting a special Gift. Although you can’t open these Gifts yourself, you can send them to someone on your Friend List. The Gifts contain a variety of helpful items and come with a postcard showing where the Gift was collected. Gifts can also contain a special 7 km Egg that, when hatched, reveals an Alola form of a Pokémon originally discovered in the Kanto region:

Source: @PokemonGoApp