The Pokémon Company has announced that Pokémon Omega Ruby and Pokémon Alpha Sapphire sold 3.04 million copies during the 3 day period between November 21st, 2014 and November 23rd, 2014. Sales include all regions except Europe where the games launch on November 28th, 2014. Japan specifically sold 1,534,593 combined copies of the games stemming from over 1 million pre-orders. Pokémon X and Y sold over 4 million copies in its first 2 days but the games launched worldwide and included European sales.

Sources: http://www.famitsu.com/news/201411/26066471.html and http://www.siliconera.com/2014/11/26/pokemon-omega-rubyalpha-sapphire-sold-3-million-worldwide-three-days/