After testing, I have decided that the optimal spread is 244 HP / 216 SpA / 48 Spe
Modest. That extra HP really helps move a few KOs back with SR, and the power difference isn't too substantial (9 points of SpA, which makes it about as strong as Timid Nidoking).
Originally Posted by Fat SJCrew
The OP should include more points as to what Nidoqueen has to offer as a special attacker over Nidoking because with the points listed, I'm seriously doubting its viability. It's advantages include a whopping 7 points of special attack over Nidoking and 'bulk' without an explanation of what it's intended to survive. The calc for Heracross' CB CC is still pretty ugly (43.4% - 50.9%) with no chance to speed tie, so unless the bulk can be put to practical use, we're essentially recommending a worse Nidoking.
Regarding your comparison, note that Nidoking is 2hko'd by Choice Scarf
Heracross' Adamant Close Combat - you're not getting a speed tie on that. Nidoqueen checks scarf cross much better.
This set should be played like a P2 with lower defenses and lack of recover, but better typing, more speed, and stronger STAB moves. That is, Nidoqueen shouldn't be expected to take extremely strong hits on the switch - but it can almost always survive them once it's in safely. Its typing and bulk makes it one of the very few checks to LO Zapdos, and it can even beat HP Ice Raikou (Earth Power does 77% minimum to +1 SpD Raikou, and Nidoqueen only faces a slight chance of a 2hko from +0 HP Ice and never an ohko from +1 HP Ice). Nidoqueen is also nearly impossible to revenge with scarfers unless it's been weakened or unless they hit it with strong, STAB SE moves; even CS Victini can't KO with V-Create, and CS Flygon's Earthquake doesn't KO it after SR damage (and sometimes not after Spikes damage). And then there's Stoutland - Nidoqueen easily survives Return and KOs back with Focus Blast (or Sludge Wave after 2 SR switchins). These are not things that Nidoking can say.
Your point was certainly valid, though...these are all things the OP should cover.
Edit: Regarding speed creep, Milotic runs 8 speed because that's what it takes to outspeed neutral-natured base 50s. Nidoqueen shouldn't be trying to outrun the milotic set on-site - if we followed that philosophy, what if someone makes a Mesprit analysis in the future, looks at the Nidoqueen spread, and goes "let's run enough speed to get to 202 so we can outspeed offensive nidoqueen"? And what if someone revises Nidoqueen in the future and goes "let's get to 203 speed so we can outrun the Mesprit analysis on site" and so on. That is the definition of speed creep, and it was a problem last generation.