Calcs have shown that Starmie deals 20% with Psychic and 30% with Psyshock to Blissey. However, Psychic deals almost double what Psyshock deals to anything other than Blissey. There is no reason to run Psyshock on Starmie ever. The boost in damage to Blissey is not worth the drop in damage to everything else. Perversity serperior may be strong but is easily killed and completely predictable, as there is.no reason to use Serperior except for Perversity Leaf Storm. It is also easy to counter as Air Balloon Heatran tanks Leaf Storm and resists or is immune to HP Ice/Fire, and can strike.back with Flamethrower/Fire Blast. Scizor can 4x resist Leaf Storm and hit back with HP Fire or HP Ice, as long as Serperior runs HP Ice so Scizor doesn't get killed on the switch. Nidoking suffers from weaknesses to common attacking types so will generally die. It's good as a suicide sweeter, but there are better pokemon out there. Also, Starmie can kill it easily as not only is ScarfMie faster (I think most Starmie are faster, since they hit 361 speed), but it also generally carries Surf/Hydro Pump and Ice Beam, sometimes even Psychic (though Psychic is rare), all three of which hit Nidoking for SE damage. Actually, Perversity Leaf Storm also hits Nidoking Neutrally, which becomes SE on the second hit (SE is x2 damage, which the +2 boost is equivalent of). So you can see why no one uses Nidoking.