Nidoking outclasses Nidoqueen by far. Nidoking gets Megahorn and has high Attack and Speed, so he's an excellent Choice Bander. Nidoqueen has a poor movepool, and the only thing it can do to make up for its lower Speed is to paralyze the foe with Body Slam. If Nidoqueen could get Bulk Up/Curse, it would be great with Sludge Bomb, Earthquake, and Rest. Since it doesn't, there's really no point in using Nidoqueen at all when you have Nidoking. =/