Nidoking has good Sweeper stats, movepool and ability.
His 85 SpA and Spe may seem mediocre, but in the UU tier it sees heavy usage.
It sees a lot of time as a special attacker because its Special movepool significantly outweighs the physical. It's ability Sheer Force combined with Earth Power among others leave a huge dent in many things.
Here is his movepool. Here are suggested sets you could run.