Chapter 148: After training on Greed Island, Killua goes back to take the Hunter's Exam. 1489 people including himself joined that year. The goal of the first trial is to take five tags from five other participants, and present them to the Hunter in charge of the first trial. Within one and a half hours, Killua takes ALL of the tags from every participant, resulting him him passing the Hunter's Exam within record time.
Following that, Gon stabbing through Pitou's torso with his own sliced off arm. Can you say GARmoe?
Leorio's return to the spotlight. He publicly calls out Ging for refusing to visit his hospitalized son. Words don't seem to have an effect, so he flips him off and sends him flying with an uppercut, courtesy of his brand new Nen ability. In-universe it's acknowledged as awesome enough for a standing ovation and enough votes for him to take over as hunter chairman to rocket him from an unknown to third place.
The entirety of the fight between Kurapika and Uvogin. In fact, any climax of the entire Yorkshin arc may account for this.
During the Troupe's attack at the auction, Zenji antagonizes Kurapika for not partaking in all the action and instead following his boss's orders to get Neon to safety. Kurapika, having other things to worry about, dismisses him with a fist in his face. In both adaptions, the impact puts Zenji on his ass, with a broken nose. In the 1999 adaption, he is sent flying into the wall, spinning no less. He attempts to exact his revenge by thwarting Kurapika's duty to purchase the Scarlet Eyes, but this fails. Then, desperate to one-up the Kuruta, already pissed off and depressed because of the events of that night, he intercepts him on the street, preparing to shoot him with a handgun. Once Kurapika lifts his chin, revealing his own blazing scarlet eyes, along with a token of advice to not fuck with him, Zenji drops to his knees in terror.
Even before Nen was introduced as a power, the series had a high amount of awesome. During the final fight of the Hunter exam for example, Gon displays his Determinator skills in his fight against Hanzo — by fighting on even after the guy breaks his arm.
Also notable are a few moments from the third part of the Hunter Exams. The heroes face off against a group of former criminals, each of which trying to challenge them in a different way.
Kurapika and Killua both curb-stomp their respective opponents.
Gon tricks his opponent into defeat.
And Leorio uses his skills as a doctor to force Kurapika's opponent (who was playing dead) to give up.
And Tompa gets one for being a bastard full of Schadenfreude and getting away with it. At least up until the next part of the exams.
Killua proves once again that he is capable of curb-stomping just about anyone during his fight against a triplet of rival aspiring hunters in the fourth part of the Exams. He defeats all of them without getting a scratch.
Also Gon escapes a cave full of poisonous snakes and sleeping gas. By holding his breath. For nine minutes. While carrying his friends.
But first he has to get the antidote to the snakes from the guy who put them there (who's sitting in the cave as well and is now dead, half the snakes commanded to guard his corpse) to save Leorio. His solution: Just reach on in there and get bit by every single snake while he fishes around for the antifote.
Killua gets another one in the second Hunter Exam he takes. Out of 1498 candidates, he's the only one who managed to pass the exam. Because he defeated everyone else in the first phase within one and a half hours.
Silva's Dynamic Entry during the Chimera Ant arc consists of him coming down from the sky with enough force to squash a commander-level Chimera ant like the insect that it is.
And before that, Zeno turns his Nen into a dragon.
Netero not only displays Nen skills no other Hunter in the series had ever shown before, he also blows hismelf up in a NUCLEAR EXPLOSION to finish the Chimera Ant King.
Which, by the way works in the end.
How it works is a CMOA in and of itself for Togashi. Typical Shounen series would do one of two things. The villain would be vaporized or would survive. The villain survives, and is soon restored back to full health plus some by his underlings (typical shounen) only to have it revealed he and several others who survived nearby are still dying because of radiation poisoning.
Chapter 334 when Pariston explains his and Ging's modus operandi.
Kurapika using his brand new nen chain to - not deflect, not dodge - but CATCH bullets fired at him during his first Hunter assignment. In the original series, the entire scene is made up him swiftly whipping the chain this way and that, skillfully taking the visual badass level up to a gazillion.
Gon's Batman Gambit against Bat and Owl, using their formation to lure Bat to a mountain side before picking up a tree and smash her with a giant gust of wind.
Gon breaking Illumi's arm.
For a villainous example: Uvogin is paralyzed from the neck down and faced with three highly skilled, super-powered assassins. What does he do? He bites the the top half of the first assassin's head off, spits it out with such force that it shoots right through the second assassin, and then yells so loud he explodes the third one's brain.
Killua ripping out Jones the Dismantler's heart before he even realizes it, then crushing it in his bare hands. It's the first time we get to see just how badass Killua really is.
Ging's description of Leoro's new Nen ability and his theory for why Leorio created it: as a surgical tool. Leorio can literally punch out cancer. Bonus points to Ging since he copied said power after being hit by it once.