Looks like a Gengar, but with Mega scary poisonous smog surrounding his body.
What I think about Mega Evolutions :
At first I tought that Mega evolution was a risked move that could kill the franchise, but after reading more informations about it I concluded that it was not a bad concept after all, but I hope that the mechanics will be well implemented and that there is a deep and convincing story behind this whole new discovery.
However, I still think the name that was given to this process is dumb. Why naming it "Mega evolutions" while it is not a proper evolution but just a temporary form with boosted Stats/Type/Ability. If this is considered evolution then Deoxys forms could also be considered "Mega evolutions" somehow too. The process is different from Evolutions and Form Variations we've got so far, they should had came up with a more specific term that describes the DNA temporary upgrade. The "Awakening" used in the Mewtwo's movie was more acceptable, but it does not refer directly to genetics.
I tought maybe calling the process "Mutation" and then adding the prefix "DNA" to Pokémon's name, exemple : DNA Gengar. Or "DNA Extensions" and adding the prefix "EX", exemple : EX Gengar. Or calling it "Promotions" and adding the prefix "Pro", exemple : PRO Gengar.
I'm not sure about those ideas, but at least remplacing "Mega Evolution" by a less confusing term. And that way we end up having three transformation classification with decent terms :
- Evolutions : Permanent transformation.
- Variations : Non-permanent transformation. Can switch between forms.
- Mutations (Mega Evolutions confuse me a lot) : Battle-only transformation with Stats/Type/Ability improvement.