When you download Pokémon Bank, you can also download the
linked application Poké Transporter. Once you insert an eligible Game
Card into a Nintendo 3DS system, you can use Poké Transporter to
transfer Pokémon from these games into their own online Boxes. Then, you can
easily transfer those Pokémon into Pokémon Sun and Pokémon Moon using
With Poké Transporter, you can easily transfer any of your Pokémon using a single Nintendo 3DS system. It could be a cool Mythical Pokémon, a Pokémon you got from a trade with a best friend, or a special Pokémon you spent dozens of hours training for competitions.
Note that Poké Transporter cannot return Pokémon to their original games after they have been stored in an online Box.