>Some theorize that in ancient times, people tormented by Regieleki fitted the equipment on the Pokémon to restrain its powers.
>Folklore tells that the Legendary Pokémon Regigigas tried to create a Pokémon from crystallized dragon energy but ran out of crystals and was only able to complete the head.

Does this allude to some type of 'upgraded' or 'unrestrained' forms? Might it be possible that the other Regis could get something similiar too? Perhaps their BST getting boosted to Regigigas' level.