http://www.newsweek.com/pokemon-shiny-poipole-distribution-event-gamestop-how-download-1123889

To celebrate the release of the latest set in the Pokémon Trading Card Game, a special Poipole will be distributed via GameStop to trainers in America.

Shiny Poipole is the special Pokémon in this distribution, giving trainers a very rare Pokémon for battling or their collection. However, to obtain Shiny Poipole in America trainers will need to head to their nearest GameStop and ask for a code to use in their Pokémon Sun, Pokémon Moon, Pokémon Ultra Sun, or Pokémon Ultra Moon game . No purchase is necessary to receive the card containing the code.