Charizard may be a faster drummer then hihidaruma, but only 5 more speed is not worth taking over 56 more attack and no double sr weakness.Ulgamoth. Might as well use the full romanization.
Reason? Belly Drum. Fastest user of it. Charizard is. (Not counting Smeargle, he's a big cheater.) That's pretty much the main reason.
And it's not like Ulgamoth doesn't also suffer from the SR problem. :0 If you're using Charizard, you probably take the same countermeasures as you do with Ulgamoth... get a Spinner.
And unlike charizard, moth is actually worth the effort of clearing rocks for due to massive sweeping potential after a boost. They both have the same problems but moth has a very powerful boosting move and can contribute beyond a few decently powerful attacks once accommodated.
Charizard is a subpar pokemon, that's all there is to it.