Need some extra incentive to download and subscribe to the Pokémon Bank app, which lets players store up to 3,000 Pokémon and transfer them between games? How about a complimentary Celebi, which will be offered to anyone who downloads the app prior to September 30, 2014.
That gives you plenty of time to decide, since Pokémon Bank is set to arrive in the Nintendo 3DS eShop in North America on December 27. Download it before January 31 and you'll get a month-long trial, after which it costs $4.99 per year.
Celebi comes with the move Hold Back, a restrained attack that leaves opponents with at least 1HP so they can be more easily captured. Use the Pokémon Link feature to transfer it to your own copy of Pokémon X or Pokémon Y.