Pokémon Omega Ruby and Pokémon Alpha Sapphire announced

 Spoiler

"Take all three of the Pokémon to the Island Cave, and make Regice hold a frozen item such as CasteliaCone, Snowball or Never-Melt Ice, and have Regice have a nickname, and Regigigas will challenge you"

wtp, that's...oddly specific.

Naw, give him Blackglasses and name him DatGrass. Because he's cool like that.

Jokes aside, it's probably fake. You probably only need the three Regis, that's all.