I don't see why the Rose he brought up so much, it is more powerful than adult Gon's Rock and Meruem would have died without his guards. Adult Gon's Rock is not going to one shot him either.
Three Rock should be enough yes.
Kurapika's being very proficient at Enhancement is due to Emperor Time, it is his Specialist ability and even with this he can't be better at it than a natural Enhancer. So Meruem can't be better at Enhancement than Gon. He didn't really eat many humans with Nen, only one, it was the bodyguard of the body double of Ming Joli-ik, he spent his days playing against Komugi without eating anything. Pitou felt his aura here and said adult Gon's aura was comparable to him. I don't know who has more Aura but the difference between them must be insignificant. Due to being an Enhancer and reaching a level with an exceptional physical condition + an incerible volume of aura comparable to Meruem himself, Gon's physical strength is certainly superior, same for his Nen attacks.Honestly the way i see it, Meruem is a specialist. And as the show's basically outlined, Specialists develop random abilities that usually don't correspond with staggering efficiency (Aka Kurapika who can use all areas of Nen at 100% when his eyes are red). I'd say the King is definitely an enhancer (unless his arms just contain enough strengh to cut through netero's aura shroud and limbs naturally...). And we know from anime muscle mass =/= strength, although Adult gon (or super gon, whichever you prefer) is definitely a towering man-beast but if muscles ment the world then Ging is in trouble.
In a show down of Aura, I'd say Meruem has more (Just from the fact that he spent a while hunting down 'rare' humans and he is the epitome of Auras collected for the Queen while she was pregnant). And If enhancers strength = who has the most aura *(times) natural physical strength. I'd say Meruem wins. He has enough aura to absorb a zero hand's shock wave for the most part, then turns around and shrouds himself from a nuke going off within less than 15 feet from him. Although he almost did die, the fact that his aura protected him from being atomized and being completely liquefied in the lava is MORE than impressive. Plus his normal strength (without aura enhancement) seems to be alot more than any normal human being should be able to achieve. But hell this is Gon, so let's say his physical strength through years of training mirrors the strength of a supposed genetically superior creature whose DNA was hand picked from the finest reserves. His aura still seems to be leagues over Gon's, and this is just strengh. Factor in Strategy, speed and mid combat flexiblity (Meruem has more means of attack *factoring in his tail* Smaller frame and lighter body weight) and the odds just seem to me more in Meruem's favor. In my humble opinion.
Zero is not powerful compared to Rock. Netero is no more at his prime and his aura is not even comparable to that of the Royal Guards, Gon's aura is much more powerful than this. It is equivalent to Gon's sacrifice but the power is not the same. A simple kick of Gon is more powerful than Netero's palm attack.So you're arguing that Gon (a human) is more durable than the King?
No.
For a display of Meruem's offensive ability = Meruem was able to rip his arm off and two limbs off Netero, all done in one quick swipe. Meruem is more durable than Pitou. He was able to rip a limb off himself. Do you really think he couldn't rip a head off Pitou with full strength?
Gon, meanwhile, seriously messed up BUT failed to kill Pitou with one hit from his strongest Hatsu (which needs to be charged). So we know he would not be able to one-shot Meruem. We don't know exactly how much more durable Meruem is over Pitou. But Meruem tanked Netero's Zero Hand. How weak do you think that attack is? It cost Netero his entire aura. It is equivalent in cost to Gon's transformation! Do you really think it'd be that weak? I'd assume it be at least be enough to seriously injure Pitou (like how Gon's Jajanken did). And yeah, considering the cost, I would totally put bets on it having power close to a Jajanken. Sacrifice my entire aura pool and life for a single attack close in power to that of an Emitter's basic Hatsu - I'd say that's fair.
And Meruem TANKED that.
Being nice to Gon and lowballing Meruem's durability, I'd say Gon would need to land at least three jajankens on Meruem to put him out.
I'm glad no one's trying to debate a fight with post-Meruem.
Three Rock should be enough yes.