Evolving Mega Altaria costs 300 Mega Energy the first time, and 60 Mega Energy every other time.
Standard game images
There is a very low chance that you can get a shiny Mega Altaria, which has the following appearance:
Acerca
"Altaria baila y revolotea por el cielo entre ondeantes nubes que parecen de algodón. Al entonar melodías con su voz cristalina, este Pokémon deja a sus oyentes embobados y admirados."
