The Pokémon Bank (Japanese: ポケモンバンク Pokémon Bank) is an app available for download for the Nintendo 3DS on December 31st, 2013 through the Nintendo eShop in Japan, and February 4th, 2014 in Europe, Australia and New Zealand, and February 5th, 2014 in the Americas. This app can be used alongside the Pokémon X and Y and Pokémon Omega Ruby and Alpha Sapphire games. Due to server costs and maintenance, to use the service there is a cost, however.
In the Pokémon X, Y, Omega Ruby, and Alpha Sapphire games, there is a way for players to store the Pokémon they receive using the traditional PC. However, the space is limited, similar to previous games. As such, the Pokémon Bank is an online cloud storage system which allows players to store their Pokémon online, in a secure manner. There are 100 boxes, with 30 Pokémon maximum per box, which allows the user to store up to 3,000 Pokémon using this cloud storage.
Due to having the potential of 3,000 Pokémon in the Pokémon Bank, there is a search feature which allows the player to narrow their search down, using specific fields such as the Pokémon's type.
In addition to this app, there is another downloadable addition you can add to the Pokémon Bank called the Poké Transporter. This addition to the app allows you to easily send Pokémon from the Generation V game series to your Pokémon Bank, allowing for easy access.