Reborn using the F-word when the boss of the Arcobaleno and granddaughter of a friend gets threatened.
In Chapter 122, he finds out Xanxus' plans involved placing the 9th in Gola Mosca which was draining his life force and killing all of Tsuna's guardians at once. After he says this the Cervello tell him that he should refrain from making accusations against their opponents. He basically tells them to go screw themselves and for the first time they look terrified.
In the anime. Reborn and Leon get several during the Arcobaleno Trials. Taking out Hibari with one move? Yup it's there. Demanding EVERYONE to attack him all at once? Check. Taking them all out with not one of them even landing a hit on Reborn? Check. Shooting down Tsuna in Hyper Dying Will Mode with his ultimate attack? OH YES! And it's implied that Reborn was barely using his strength. Tsuna only managed to get a scratch on Reborn because Reborn gave him a chance to! If Reborn got a little serious, the entire episode would probably last 5 minutes. Reborn is a BADASS.
Any moment involving Tsuna getting shot by the Rebuke Bullet is a Crowning Moment of Awesome.
Tsuna: "If I were to lose a dear friend right in front of my eyes...I'd never be able to die in peace!"
How can you not mention Tsuna's fight with Mukuro in the Kokuyo arc? AWESOME. Especially the end where he fucking slams his X-Gloves into Mukuro's face and then forces him to the ground, where he passes out.
Chapter 98: Twenty Years into the Future Lambo.
Chapters 116 & 117: How has Mukuro's CMoA in Chrome's fight with Viper not up here yet? Chrome's getting completely overwhelmed, only to have Mukuro intervene and shred the punk. Just that fact that he can out-cast the master illusionist of the Arcobaleno is badass in and of itself.
Chapter 125: Reborn gets one in this circumstance when the Sky Ring Battle commences. The Cervello tell him that once the fight starts, nothing interferes; no advice, no special bullets, nothing. Then Xanxus punches Tsuna in the face. The following dialogue ensues:
Xanxus: "Oh, I'm sorry, did I get him before he could be shot with his bullet?"
Reborn:(twirls smoking gun) "Nonsense, who do you think you're talking to here?"
During Tsuna's fight with Xanxus, when he first utilizes his X-Gloves. This was made even more awesome when Xanxus unveiled his guns, only for Tsuna to calmly suggest that they "try them out" and see who is strongest. Then he attacks. His Bad Ass levels sky-rocketed.
This troper never liked Ryohei much, but still found the fact that in Chapter 132, he demolished the school gym with one punch very very cool.
Regardless of whether they won or lost, every main character got one in the Rings Battle.
Chapter 153: Gamma reveals to Gokudera that the Tenth Vongola Boss was gunned down in plain view of many of his subordinates. Gokudera then dives into a fight with Gamma he definitely won't win. When he loses Gamma tortures him for information and Gokudera responds by spitting in his face.
Chapter 164: Chrome creating real illusions of her allies during her fight with Glo Xinia.
Chapter 240: Byakuran comes out of the sky and shoots a giant laser from his eye. This may not be a CMOA, but it is definitely a Crowning Moment of some sort.
Within that same chapter, Tsuna's family had to raise five million fiamma volts; something treated by the others as absurd. They are given a brief period of time to do so, and wait until the last second anyway (as they were waiting for Yamamoto and Hibari to show up.) Then, within the last possible second, they simultaneously open their Vongola Boxes and proceed to achieve twice the required amount. Even Byakuran stopped smiling by that point! BYAKURAN!!
Explanation: Tsuna was trapped in an illusion that made him fly in circles. He X-BURNER'd his way out.
Hibari... just Hibari. He might as well be a living example of a Crowning Moment of Awesome.
His battle against Gola Mosca in Chapter 119 is all the evidence you will ever need.
You mean despite the fact the fight was fixed?
He managed to rip off the arm of a robot within seconds after promptly crushing its head using his Tonfas. Fixed or not, winning the ring in less than 5 minutes? With a robotic juggernaut? Genuine CMOA material right there.
Not to mention the robot was said to be invincible by Tsuna's dad and company.
Hibari appears in Chapter 261 to have killed Daisy of the Real Six Funeral Wreaths with his Vongola Box.
Well but that's Hibari. I'd also like to point out how, during the Sky Ring Battle, Hibari managed to overcome poison which could've killed an elephant, knock down a pole and save himself while everyone else was still either agonizing or being saved by someone else. And then he appeared in front of Belphegor to just, generally, be awesome.
Chapter 264: Fran of the Varia gets one by tricking the Vindice and having them release Mukuro instead of the last of the Six Funeral Wreaths, Ghost.
Vendicare Prison Guard: "Who ever could trick us? There are just three illusionists who are strong enough..."
Chapter 266: Gokudera after over 250 chapters has openly defied Tsuna's direct orders. Thus getting quite the 'Oh shit!' reactions from everybody.
Chapter 268: Lambo managed to beat Kikyou's dinosaur box animal with his Vongola Box Weapon. Granted not the most amazing method... but he just killed a fucking dinosaur.
Not just one...7-8 OF THEM.
And the owner of those dinosaurs, Kikyou, is the one that claims to be the one with the most power of the Six Funeral Wreaths.
And the owner of those dinosaurs just got PUNCHED in the face by Ryohei. Seriously. Punching dinosaur-hydra-monster-thingies in the face? Can't get much more extreme.
And the said owner also claims him to be hands down the strongest human he has ever fought.
Chapter 270: After the dinosaur spam, Mukuro shows up with an illusion that not only tricked the Six Funeral Wreaths but was enough to have them use each of their hell boxes first. On top of this, he did so withoutusing a Vongola Box.
Chapters 275 & 276: After Byakuran's power-up, and "round" with Tsuna, Reborn still believes that Tsuna will win. Even after it appears that he slit/cut/crushed his neck.
Reborn: "Don't underestimate the strength of Tsuna's Dying Will. Besides, I'm not talking about whether you can win. Tsuna, you've got no other choice than to defeat Byakuran."
Chapter 278: Tsuna just got a Awesome Moment of Crowning by being officially accepted as the 10th Vongola Bossfrom the First himself. A little later on, he turned that into Crowning Moment of Awesome with the amount of power he just received by blocking and countering Byakuran who just easily Curbstomped him not so long ago.
Vongola Primo: "Now give that Mare boy what he deserves."
And just a few pages later:
Byakuran: "Haha, too bad. I've only shown eighty percent of my power so far."
In Chapter 293, Kaoru gets one for critically injuring Yamamoto of all people considering how he runs on "instincts" so damn well to the point of hospitalization is pretty badass regardless of his face heel turn. This is continued in Chapter 294 when Tsuna quite simply sent shivers down my spine for accepting the ceremony to fish out the culprit knowing full well where this choice is taking him. Note that he did this without his Dying Will ModeShit just got real.
Chapter 372: Fon vs. The Varia. Varia's on the ropes.
Chapter 381: Mukuro uses his flesh eating crow illusion on the Vindice.
At the end of Chapter 382, Chrome shows up to help against the Vindice while telling Mukuro that she will help with the illusion and fight as well. She does so even though she's "seriously ill" as M.M. says.
Chapter 383: Chrome proceeds to use her own illusions to replace her organs, showing that with her new found motivation she has a very powerful Dying Will Flame. She then combines her illusions with Mukuro to make THIS.
Chapter 385: Reborn basically tells Bermuda to go screw himself after being offered the opportunity to join him.
In Chapter 390, Tsuna tells Reborn that he's a failure as a home tutor and he's not gonna let Reborn die.
Chapter 402: Reborn vs. Bermuda. And then Reborn shoots Tsuna with a Dying Will Bullet while Tsuna's in Hyper Dying Will Mode.
Chapter 403: Tsuna epic one punch defeat of Bermuda.