Tough one to answer.
Personally, I wouldn't. Fire type are terrible as gym defenders already, and even if you're going to put one in you're better off with Arcanine. But you know some kid going to beat it with a Vape half its CP.
Kind of stinks that Charizard is the least useful starter. He's more for the Pokedex than anything else.
I have a 91% IV Charizard with Wing Attack/Dragon Claw and I barely use him.