Sorry for the long absence here, been doing a lot of commissions and other stuff I cannot talk about. Enjoy this quick sketch of Realistic Mega Charizard. I lost my shit when I saw him, super cool. To answer a few questions: Yes, I have a plan for what mega evolution is in my take on the Pokemon world, but I will reveal it later. Yes, I like mega evolutions. Yes, there is more new Pokemon art coming soon. The mega Pokemon I most want to see are MegaMeganium and MegaYanmega if only because of their names.
I don't know if this is what you'll go for, but they could be mutated forms of the original that use the mutations to their advantage. For example: mega charizard y uses the small fins on its arms to be more aerodynamic as the original is quite 'podgy.' Once exposed to unique stones, a trainer can accelerate the mutation process.