New download-exclusive software for Pokemon - Pokemon Bank: an online storage with 100 total boxes, allowing you to store a total of 3000 Pokemon. PokeTransporter: allows you to transfer Pokemon from Black/White/Black2/White2 to Pokemon Bank, therefore allowing you to use them in Pokemon X/Y. Pokemon Bank is required for activation of PokeTransporter. Pokemon Bank is a paid service - there is an annual fee ($5, according to the Japanese stream). There will be a free trial period for this service upon initial release. They also mentioned compatibility to future games. Additional details for Pokemon Bank are available on the official website.
Other information - Your first partner Pokemon (Chespin, Fennekin, Froakie) wont be given to you by the professor; it will, instead, be given to you by your friend. Professor Sycamore will be giving you one of the original starters (Bulbasaur, Charmander, Squirtle) Venusaur, Charizard, and Blastoise all have Mega Evolution forms. The special edition blue 3DS XL, as well as a matching red 3DS XL, will also be released in North America and Europe on September 27.