Mega Evolution in Mutia is entirely a result of people bringing it from outside regions, particularly Kalos of course. There are no native Mutia exclusive Mega Evolutions, as they generally had little to absolutely no effect on Mutia's ancient history. The only new ones that come to the table of Mega Forms for old Pokemon from regions such as Unova, Johto, etc. Xatu, Obstagoon, Krookodile, Relicanth and Hydreigon.