Early visitors to the world of Johto can get a cool bonus for their system in the Nintendo 3DS family. If you purchase Pokémon Gold or Pokémon Silver via Nintendo eShop before January 15, 2018, you’ll get a cool new theme for your Nintendo 3DS. You’ll either receive a Pokémon Gold or a Pokémon Silver design, depending on the game you purchased. Look for the code to download the theme on your Nintendo eShop receipt and take the beauty of the Pokémon Gold and Pokémon Silver wherever you go.
Source: Pokemon.com
Pokémon Blog 