Okay, so I've seen so many sets for Nidoqueen/king (for this set I like nidoqueen because of the pinch of extra defence) This is more of an annoyer, it can give a big advantage over teams that: A) Have a lot of Pokemon that are effected by both ground and poison, B) have Pokemon that LIKE to stat boost, and C) (the best case scenario) Pokemon that NEED to stat boost before they can really take down Nido. the best part about this set is that you can use it in UU. So lets get to it.
Gen V of course
EV: 252HP/Split Def and SpDef/4Att
give a nature for one of the defences, I usually give extra defence EVs and nature boosts SpDef
Ability: Poison Point (extra chance for poison)
Item: Black sludge (gets extra HP and punishes choice switchers) or Focus Sash (if you want a guarenteed toxic spikes)
Now this is a very good set if it works, which I've noticed works probably 60% of the time, there are, however, a LOT of counters to this set, but in general this set at least puts toxic spikes on the field and you can usually get a switch or two in. Here's the basic formula for how to use this.
Put out a toxic spike, if they used something like curse or acid armor or cosmic power you have just accomplished half the battle. at this point you can make a guess, you can either guess they're going to keep upping their DEFENCE for at least another round and put out another toxic spikes or even a stealth rocks to have almost assured damage for foes not effected by toxic spikes. OR if they up their attack your best bet is to use dragon tail to switch them out and hope they don't OHKO you.
If you get as far as puttin out the spikes and all, You can start making decisions. Lets say that theres a scizor out, if he does a bullet punch for 49% damage, then you can use protect to gain back enough HP to take another hit and put out a dragon tail, which then puts out another decision, you're stuck on low HP and they send out something that has ANY attack to kill you possibly. If you have enough HP protect and take another hit and throw out another dragon tail, but if you happen to be faster, then you can try to throw more field hazards out before you die. or if you're slower, you can maybe try to switch out, but it isn't really worth it.
Now you've set up a great field and maybe poisoned some and damages others. The best thing to do with Nidoqueen here is to have a couple of tanks in your party, or more sponges. My favorite is to use Nidoqueen in the UU tier, for you will have less of a chance getting OHKO, but I still use this set in OU as well. So in UU, I love having a Clefable with magic guards. No poison, weather, or any shenanigans like that, and then give it leftovers, cosmic power, 252HP split defences, and something like stored power (260 base power with +6 on both defences) and then softboiled and you are unstoppable, you just wait for poison to take effect, occasionally throwing out stored powers. Watch out for dark types though.
and now I've rambled, but I wanted to share this strategy/set.