I don't know about uncompetitive, since it's not like the only way of beating it requires you to keep a sleeping pokemon in against it. Broken yes, though. Sleep Powder is almost a free boost, and at that point you have to hit it from the physical side to kill it quickly (not killing it quickly or phazing it means death). Most physically offensive pokemon are weak on the special defense side, so taking a boosted bug buzz is a tough proposition, and of course it's faster than most everything after one boost as well. RU has no shortage of good Special pokemon who can wreck everything with a Quiver Dance under its best. Even tanks like Taunt Samurott become godly sweepers at +1/+1/+1. If you get two boosts then forget about it.
I'm not 100% sure this is broken (as opposed to just massively centralizing) but I'm not going to complain about it's suspect status because this thing makes building a team kind of a bitch. Not the hardest to counter, but you have to use shit you really don't want to use. Most of the things that do wall it will die if they get a Special Defense drop from Bug Buzz, and those that 4x resist can't switch in on Air Slash. Speed Boost is easier to wall but it fucks any speed based strat badly.
Omastar, Gorebyss, Huntail: Do not ban
Since when were these overpowering? The metagame is so full of boosting Special sweepers that stuff like Haze Cryogonal and Special Defense Blastoise are great even on balanced teams. The only kind of teams that aren't generally prepared for these types of shenanigans are super offensive ones; the kind that make it really hard to set this stuff up and usually carry priority to clean it up if it does. I understand that they don't want to bother with suspect testing for this but when something is suddenly on the chopping block that makes so many of us say ".....whaa?" (especially Omastar) I really want to know how this decision was reached. I'm not going to go so far as to say these are bad or not threatening but considering that they all have rather dismal Special Defense it's not exactly easy to set them up. I'm not going to say these are terrible, but at this point in the metagame if you can't deal with these then you are probably going to lose a majority of matches to other special threats. Sure many of these may be leaving us (Yanmega, Venomoth, Cresselia) and the metagame may shift to a point where these are harder to deal with, but right now it's not the case; and we shouldn't be banning something based on what we think will happen to the metagame in the future.