To get the ORAS demo code you need to do any one of these things, codes will be distributed at select cinema locations nationwide from Nov. 7–Nov. 13 (while supplies last).
Check with your local retailer during the holidays to find out about special demo code giveaways (while supplies last).
Get a code with your purchase of the new Pokémon Art Academy game (out Oct. 24) when you buy from Nintendo eShop on your Nintendo 3DS or 2DS system
You’ll also get a code with your purchase of one of two classic Pokémon games coming to the Virtual Console service on Nintendo eShop: the Pokémon Puzzle Challenge game (out Nov. 6) or the Pokémon Trading Card Game (out Nov. 13). You'll find your free demo code on your eShop receipt (download codes available while supplies last).
Codes will also be distributed during the holiday mall tour from Nov. 24‒Dec. 21 at 16 different locations throughout the nation. Talk to a staff member to try out Pokémon Omega Ruby, Pokémon Alpha Sapphire or any of the featured Nintendo 3DS games to receive two codes—one for you, and one for a friend (while supplies last). Check back soon for a list of tour locations.
And the Shiny Gengar codes stopped being distributed October 26, and Diancie codes are being distributed until November 16
Hope I helped <3