I think Charizard, as it has a powerful attack stat and as it it part flying type, whereas magmortar would get beaten up by a ground type, Charizard has good chance of being imune to some attacks, and could use flying type moves to pound the opponant, while Magmortar flails around trying to dodge with its low speed stat. And with a powerful attack stat, a fire type could clobber most pokemon, with only a few exeptions, like in Charizards case, electric, water and dragon types.