but then what's left of me?
About typing, Swamp-Rockets post about Quagsire implied its typing is redundant with Poliwrath because it resists rock, my point was that they aren't redundant because Quagsire's typing supplies it with less weaknesses, and an immunity. You also talked about how it certain mons have ways to get around Quagsire (HP Grass Manectric), but that's usually obvious when they switch them in (forcing switches is a good thing in a stealth rock meta).
I was talking about the curse set (252HP/252+ SpD).
Have you used the curse set? If you haven't then I believe that my evaluation of its abilities is more useful than yours, because I have. Of course it requires support (although massive is a hyperbole), I even pointed out that it needs team support (things with grass type moves as well as toxic users removed and something to take grass type moves). That being said, teams that have their Quagsire checks removed (usually 1-3 mons) will sit there as it slowly boosts up and then eats the rest of your team. Does any boosting sweeper not require support? Your argument is pretty nonconstructive, if you think it sucks please articulate why.
Yes, Quagsire is undoubtedly C. And I agree there are many reasons to choose other bulky waters over Quagsire, but unaware, recover, and curse give it enough of a niche to stay where it is. It should remain high C as the only pokemon in the tier with Unaware (notable niche) and its biggest flaw is that it faces lots of competition with in its type, that's not even really a flaw (obviously there are other flaws, but this is the one being brought up the most).
4- SpA Entei Hidden Power Grass vs. 252 HP / 4 SpD Quagsire: 236-280 (59.89 - 71.06%) -- guaranteed 2HKO
curse sucks simply. requires massive team support to work, and even with it, quag probably fails cause it's horrible.
C Rank: Reserved for Pokemon that have notable niches in the RU metagame, but have just as notable flaws that prevent them from being top tier threats. Pokemon in the C tier often require significant support to be as effective as higher ranked Pokemon in RU. C rank Pokemon tend to face a lot of competition with the more commonly used Pokemon.