Face it, iKhanic. Volcarona is suffering more than Charizard. SR is literally the only thing that keeps him in OU.
SR the only thing keeping Zard out of UU.
Also Volcarona can handle switching into SR. It's bulkier and doesn't lose an 8th of HP per turn, so it can afford to run roost. I agree it would be Ubers without SR, but it can still handle SR better than Zard can.
Victini, better sun sweeper than Charizard. UU Darmanitan, better sun sweeper than Charizard, UU Liligant, better sun sweeper than Charizard, RU I think Sawsbuck, better sunsweeper than Charizard, NU Leafeon, Shiftry, Exeggutor or however you spell it, all NU. all better sun sweepers than Charizard.
Oddish. little cup. better sun sweeper than charizard
The question had nothing to do with tiers anyway. The question is which Pokemon is most hindered in battle by SR. Zard does have other things affecting it negatively, but the fact of the matter is that switching into SR is worse for Zard than it is any other mon barring maybe Dragonite.