Charizard was always bad, even before Stealth Rock.
Gen 1: Before the Special split, yeah, he had some issues with a base 85 special stat. Gen 2: He made it up to BL, that's not too bad.
Charizard has a pretty good attacking movepool IMO, able to learn several fire, dragon, and flying attacks. Plus some others. Plus he has belly drum.
Solar Power's not bad either despite its nasty side effect.
What kills him is the typing. The only other pokemon that have that typing are legendaries with higher base stats in almost every category but speed. On top of that, Fire and flying share two resistances and two strengths, so the extra type doesn't help as much as it hurts by adding an Electic and Rock weaknesses while making Ice attacks neutral.
Not saying that without his bad typing he'd end up OU, but I don't see why he couldn't make UU.
Not changing this sig until we get a new main series Tales game released on a Nintendo console in the US