I have a Charizard in Pokémon Go but there is no option for it to Mega Evolve. It works for other Pokémon but not for Charizard. I also got it before Megas came I think. So why won’t it Mega Evolve?
You need 200 Mega Charizard energy to mega evolve it. If you have that amount of candy though, then it might be a glitch.