There's almost a garchomp-like situation with scyther in UU.
No there isn't, nothing of the sort. In fact in my experience I've only seen about 4 or 5 of them in the 30-odd battles I've had in the last week and a half.
Practically all of its counters can be 2HKOed.
Only after a Swords Dance (and holding a Life Orb) which you seem to think it gets for free. Nothing could be further from the truth. My current team carries none of the supposed counters to Scyther, but 5 out of 6 of them have some way of badly hurting or crippling it one-on-one, two are faster than Scyther and can OHKO and only two are weak to either Brick Break, X-Scissor, Night Slash or Aerial Ace. I have never found Scyther to be much of a threat because it simply does not get an opportunity to set up, and ends up being worn down by Stealth Rock very quickly. I do not feel that it is a team centralized against Scyther, it is just a team that I have found to work well in general in UU. Of course Scyther was kept in mind as a threat when building the team, but no more than every other threat.
btw, you also missed Luxray w/Intimidate as a SD Scyther counter. Very underrated, but a great counter to it nonetheless.
I am not over-rating it. I accept that it's fairly easy to counter, and I definitely don't claim that it's going to automatically going to beat you if you don't put up weather. However, I am concerned by the fact that it walls so much of UU. You'll have to go out of your way to avoid being completely stopped by it with a lot of Pokemon.
Let me put it another way. Given the vast number of ways to beat Shedinja and quickly remove it from the game, it is purely the fault of the teambuilder if they haven't took precautions to mount at least an adequate defence against it, which in most cases is all it requires. On the other hand, if you are battling a team that is well prepared against Shedinja, and still manage to remove all hazards and Pokemon that can hurt it whilst keeping it alive, then a lategame Shedinja clean-up is well deserved on your part, and your opponent will be first to acknowledge that.
And Rapid Spinning honestly isn't hard in UU.
Personally I've found it to be harder than it looks due to the fast paced nature of UU, although the main reason I use it is to allow Swellow to stick around for a couple of extra turns and occasionally protect my Electrode's Focus Sash, nothing too essential. I can only imagine how difficult it is to have at least 1/6th of your team relying on the success of your spinner, given that you have to use two non-threatening turns (for your opponent) each time you need to remove entry hazards. After the first time your strategy is revealed, allowing your opponent to predict and take advantage, making your task even more difficult.
Not only that, but two UU Pokemon get the Rapid Spin + Yawn combo that basically forces a Spin unless you carry a Rest-Talking Ghost in an environment without Dusknoir/Spiritomb.
cough*Banette*cough, although point taken that thing isn't the bulkiest of Pokemon. It can cause plenty of damage to your team though if you give it too many free switches.
I've never really noticed an overabundance of Toxic.
I have. All sorts of random walls and tanks seem to carry it, and I have recently given it to my Blastoise after realizing how much it fucks up the usual switch-ins.