From Bulbanews, your community Pokémon newspaper.
Available for X, Y, Omega Ruby, Alpha Sapphire
A code card for Shiny Xerneas and Shiny Yveltal will be available at gamescom, which is held in Cologne, Germany from August 17 to 21, 2016.
The code cards can be obtained by visiting the Nintendo stand at gamescom. Each code card includes one single-use code for Xerneas and one single-use code for Yveltal.
The codes can be redeemed in Pokémon X, Y, Omega Ruby, or Alpha Sapphire. They codes can be redeemed from August 17 to December 31, 2016.
The Xerneas and Yveltal are likely the same as the Xerneas and Yveltal currently available via code for PAL region games. If they are, both Pokémon will be level 100 and have no held item; Xerneas will know the moves Geomancy, Moonblast, Aromatherapy and Focus Blast; and Yveltal will know the moves Oblivion Wing, Sucker Punch, Dark Pulse and Foul Play.