Aion

Aion is considered a myth among Pokemon, blessed by Dialga themselves. No concrete evidence has been gathered to prove their existance. Atop Mount Coronet, amongst the ruins of the Spear Pillar, this Glaceon lurks, serving as Dialga and Palkia's gatekeeper, to keep up with this task, Aion was blessed with powers to control time to an extent, but it is highly unlikely he will be granted more. Aion, granted with these powers, is able to control time around an area, as well as aging himself at will. Age does not affect his life, instead, as their age increases, so too does their size. If startled, on the other hand, it will force him to age backwards, shrinking in size.