I traded my Latios w/Latiosite to my Pokemon X, and it could mega evolve. I thought that new megas were not able to be on X/Y. Is that supposed to happen or what?
Remember that Mega [email protected] was first discovered in the coding for X and y, but was not released until ORAS. It can Mega Evolve because the coding for Mega Latias, Mega Latios, the Latiasite, and the Latiosite were originally made in X and Y.