Mega Man's original crowning moment of awesome was defeating the six robot masters and Dr. Wily for the very first time. To make it even more awesome, this was before Energy and Weapon Tanks. Mega Man was, like his sister Roll, originally designed as a housekeeping robot.
Beat being able to take down anything with ease in 5 and 6, so much so that his function was completely changed from 7 on.
In Megaman 7, if you time it right you can defeat Turbo Man and Spring Man with Noise Crush as their health bars begin to fill up.
Mega Man: I am more than just a robot. DIE, WILY!
Oddly, Rockman never says those words in the Japanese version of 7, meaning this was originally Wily's crowning moment. He told him that robots can't harm humans. In the American version, he said the above line. In Japan, he obediently powered down.
Bass trumps them both right afterward by compressing a Breaking Speech into a single phrase:
The moment in 8 where Duo takes out a huge mech Wily built singlehandedly, made even better when he cuts the freaking robot's face off, was awesome in its own right. Keep in mind that this robot was busy electrocuting a helpless Mega Man when Duo showed up, and had punched Rush into a wall when he tried to stop it.
In Mega Man & Bass, Protoman gets a moment when, after being chopped in half in the opening level, and then getting his own laser shot back at him, takes off the kid's gloves and shoots King with a Hadouken. Eat your heart out, X.
The Hadouken was a translation joke, it's still Badass and awesome, of course.
The real name of his attack is even more so: Big Bang Blast.
8 has the helper robots show up to help you in the two aerial stages. Eddie drops bombs. Beat does a bird missile. Auto, the item maker, shoots a freaking bazooka. And you can have them all on the screen at once, with Rush and Mega himself shooting their own brand of plasma goodness. And one of these is in a Wily Stage, where you even face a boss with this possible setup.
Wily has a CMoA in Mega Man 9 when he talks Light's robots into rebelling. Yes, you read that right, he talks Light's own robots into rebelling against humanity, simply by giving a very valid and true argument about their being arbitrarily destroyed after a set time despite still being very much useful as human servants. It's a shame Capcom didn't follow up on it, because it would've been an awesome twist to the entire Mega Man series.
However, it should be clarified: Wily did not convince them to rampage. He convinced them that they were still useful, and that they should let him repair them so they could continue helping people. Presumably, while he was "repairing" them, he installed their murderous programming. Still, Wily does get major points for even that subtle rebellion, since they are 3-Laws robots, and second law was in effect.
Let's be honest here — Capcom even making Mega Man 9 is a Crowning Moment in and of itself; doubly so for them essentially making a brand new NES game almost a decade-and-a-half after the system was discontinued.
Mega Man himself gets one in 9 upon defeating Wily with the Mad Scientist begging at his feet once again. He then proceeds to use Rush to show him a montage of all the times he's had to beg for mercy in the previous games as a brutal Humiliation Conga. Doubles as a Crowning Moment of Funny.
The introductions of Wily's castles have never been as awesome as the one seen in Mega Man 10. The castle gradually emerges from the darkness as the screen slowly pans it into view. It just makes storming it all the more epic.
It reached third place in the iTunes store days after its release. More significantly, it's #63 and climbing in iTunes' Top Grossing Apps. Of the 1,136 ratings, 889 of them are five star reviews; while most of those are referral codes, it shows a lot of people have the game and care enough to rate it.
Kalinka being seen again for the first time since Wily and Light's Rockboard. She helps out Over-1, too, and is older than she was in Mega Man 4.
Of all people, Dr. Wily got one in "The Mega Man in the Moon". When a human girl, Tina, stowed away on the rocket ship to see her father, Wily promptly held her hostage. When Mega came to save her, Wily physically grabbed Tina and told Mega to take a hike or else he'd activate her jetpack. Sending her into space. Mega promptly left and Wily was free to continue his plan.
Roll got one in "Terror of the Seven Seas" when she successfully infiltrated Wily's base, defeated Cut Man, avoided Elec Man and Bomb Man, and got out safely. Given her track record in season one you might be waiting for her to get caught, but it doesn't happen, establishing her as a proper action girl.
Near the end of "Mega-Pinocchio", Mega Man pretended to be evil to get close enough to steal Magnet Man's power. How did he accomplish this? With a high-five.
Protoman got one in "Bro Bots". When Mega Man found out that he was only pretending to be good, he was understandably angry. However, Mega couldn't act to stop him and Wily because of a 'scrambler chip' Proto had planted on him earlier. Protoman offered to remove it if his brother would join him. When Mega refused...
Proto Man: Whatever you say, bro. *shoots Mega Man, sending him flying into the wall*
Protoman got another one in "Showdown at Red Gulch". Wily had his robots powered up with meteorite fragments, and Proto warned Mega that he was out of his league. Mega Man ignored his warning and tried to get him anyway. Protoman's response?
"I hate to say I told you so, but..." *shoots him* "I told you so!"
Eddie got one in "Mega-Pinocchio". When Mega Man jumped in front of Protoman's shot to protect the statue of Abraham Lincoln, he was unable to move. Protoman went to finish him off... and Eddie charged up the stairs, knocked Protoman over, and gave Mega Man an Energy Can to power him back up.
The mayor of the city got one in "The Big Shake". Dr. Wily invented an earthquake machine that, well, created earthquakes. After an attack on Light's lab, Wily believed he'd killed them all. Wily then threatened the mayor, telling him Mega and Light were out of commission permanently, to submit, and to be quick about it as he had other cities and countries to deal with. The mayor refused and told him to shake the city to the ground. They wouldn't surrender. He'd rule nothing.
"Master of Disaster" was one of the...stranger episodes, but it had an awesome moment from Protoman. When Wily found a genie and ordered him to destroy Mega Man, he ignored the robots. After the genie tried and failed several times, Protoman told him to stuff it and let the robots give it a shot.
Granted, the 'bots failed, too, but he talked back to a genie.
In "Ice Age", Iceman defeated Mega Man, Roll, and Rush about 3 times in the span of a single episode. And he kicked Rush while he was frozen, breaking him into pieces.
Metalman got one in "Future Shock". After pinning Mega Man under a pipe, he tried to saw his head off. Hardcore!
"Mega X" was one for just about everyone involved, animators included, but special mention goes to Dr. Wily, who saved Vile and Spark Mandrill from X.
On the heroes' side of things, it had been shown that none of the present-day tech could affect Vile and Spark Mandrill; Mega Man experienced this firsthand. But it didn't stop him from standing in front of the time portal to stall them until X could get at them. When Vile retaliated, Mega and Rush pulled X out of the way of his shot, and when Spark Mandrill attacked them, Mega Man was able to stop his shot with a blast of his own.
Vile and Spark Mandrill are completely unstoppable until X arrives to even the odds—and even he has trouble with them.
X was attacked by Cutman's Rolling Cutter. He caught the blade.
X copied Snake Man's weapon and destroyed Wily's superlaser with one shot.
Roll got another in "Bot Transfer" when she beat up Snakeman (technically it was Mega Man in his body, but still) with a lamp.
Rush got one in "The Strange Island of Dr. Wily," where he was instrumental in helping Mega fight the giant Stone Bot, even distracting him when Mega was briefly captured. As bonus points for those who didn't much like Rush, he stayed relatively silent during the fight.
Dr. Light got one in "The Mega Man in the Moon" when he interrupted Wily by cutting into his transmission screen; generally Wily did that to the good guys.
Light got another in "Cold Steel" when, after being freed of brainwashing, said this in response to Wily's tirade.
Wily: Why!? Why am I surrounded by fools?
Light: Maybe because that's all you know how to build, Dr. Wily.
Protoman got one in "Campus Commandos," as he donned a jetpack and silly-looking goggles to see Mega when he was in stealth mode. The resulting aerial fight had Proto doing a midair somersault while vaulting down the side of a building, shooting at Mega Man mid roll.
Any time Rush goes into jet mode by himself to save Mega Man.
Mega Man is about to finish off Wily in Issue 4, but he runs out of ammo. Wily takes advantage of the situation to fly away. Rather than let Wily escape, Mega Man runs towards a piece of metal left behind by the fight, jumps off of it, and proceeds to blast Wily's machine at point blank with a charged shot, keeping Wily from escaping. Also, this is the very first time Mega Man has ever fought Wily. Can't wait for the Wily fight in the Mega Man 2 arc!
Wily's buried under the remains of his Wily Machine, complaining that Dr. Light's robot had beaten him, but "at least I'll die with the satisfaction of knowing I was the better man." Cue Rock digging Wily out to save his life.
In Ultimate Marvel vs Capcom 3, the 'Days of Future Past' stage features a poster of several missing characters from the previous Marvel vs Capcom games. All characters appearing on the mugshot poster are tagged with either 'Apprehended' or 'Slain'... Save Megaman. Overlaps with Fridge Brilliance when one realises that in a bad future where Sentinels have gone on a Terminator-esque rampage against Mankind, only Megaman would continue to fight on, for Everlasting Peace.
Even better, Version 2 was released, which fixed complaints fans had and added a bonus character.
Mega Man is in Super Smash Bros. 4 with a slew of Robot Master weapons. His Final Smash summons other Mega Man incarnations to fire a huge beam of energy, a la Pokémon Trainer's Final Smash from Brawl.
Rockman Xero by fGiMr part one and two is pretty much distilled Zero awesomeness.