North Americans! Get your level 70 shiny Rayquaza now! (OR/AS only)
As a pleasant surprise, North Americans can now receive the legendary Pokemon as well starting on August 12th through the in-game mystery gift option. All that you need is a copy of either Omega Ruby or Alpha Sapphire and an internet connection to your 3DS. This Rayquaza is shiny, at level 70, and knows the move Dragon Ascent so it is able to mega evolve. The event ends on September 14th, 2015.
So if you have a copy of Omega Ruby or Alpha Sapphire be sure to get him while you can!
source at Serebii.net