Don’t forget to grab Diancie. Mythical Pokémon Diancie is available through Monday for Pokémon Omega Ruby and Pokémon Alpha Sapphire in North American and PAL regions. I completely forgot (thanks for the reminder, Oliver!). Don’t be me.
The Pokémon Company makes Mythical Pokémon Diancie official. Three days after the Serebii report, like clockwork, the latest pocket monster movie star is confirmed. They also confirm the once-hidden Pokémon will be coming to Pokémon X and Y at a later date, but won't tell us when or how because they're mean like that.