When you download Pokémon Bank, you can also download the linked application Poké Transporter! When you insert a Pokémon Black Version, Pokémon White Version, Pokémon Black Version 2, or Pokémon White Version 2 Game Card into a Nintendo 3DS system, you'll be able to use Poké Transporter to transfer Pokémon from these games into their own online Boxes. Then, you can easily transfer those Pokémon into Pokémon X and Pokémon Y using Pokémon Bank!
Poké Transporter is a free downloadable application for the Nintendo 3DS system that will be available along with Pokémon Bank. Note that Poké Transporter cannot return Pokémon to Pokémon Black Version, Pokémon White Version, Pokémon Black Version 2, or Pokémon White Version 2 after they have been stored in an online Box.
Note: You may find yourself unable to use Pokémon Bank or Poké Transporter to deposit any Pokémon created illegally by software unauthorized by The Pokémon Company and Nintendo into your online Boxes, or to move these Pokémon between online Boxes.