Poké Transporter

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 Ultra Sun and Pokémon Ultra Moon using Pokémon Bank.

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.

Poké Transporter Notes
If you use Poké Transporter to move Pokémon from the Virtual Console versions of Pokémon Gold Edition, Pokémon Silver Edition, Pokémon Red, Pokémon Blue, or Pokémon Yellow: Special Pikachu Edition, they can only be sent to Pokémon Sun, Pokémon Moon, Pokémon Ultra Sun and Pokémon Ultra Moon. They cannot be sent to Pokémon Omega Ruby, Pokémon Alpha Sapphire, Pokémon X, or Pokémon Y.

Pokémon moved to Pokémon Bank using Poké Transporter cannot be returned to Virtual Console versions.

You cannot deposit Pokémon holding items into Pokémon Bank. If you try to deposit a Pokémon with a held item, that item will be sent back to the original game.