In his first appearance, Jara Hamee slices into his own head and pulls open the wound, revealing his brain, to prove that he's not a Controller.
Tobias: <Did that scare the pee out of you, or are Andalites okay with this kind of thing?>
Ax: <My friend, I am as peeless as you.>
Erek the Chee, programmed to be a Technical Pacifist, gets his in #26. Getting in touch with his inner Manipulative Bastard, he wants the Animorphs to kill the Howlers—the aliens that hunted his creators to extinction. After downloading the Howlers' memories, Erek learned that the species itself isn't inherently evil: evil chessmaster Crayak designed them so that they had a lifespan of only three years, and never became adults. They're eternal children who think that murder is simply a game; they don't know any better... and Erek deliberately held back this information, which, in many ways, set the tone for his role in the final battle of the war.
Erek: "Juveniles or adults, they massacred my creators, they made refugees of the Chee, they murdered my world."
Had it not been for his actions directly after, Erek might have had his earlier, when he massacres a squad of Hork-Bajir off-screen with such little effort it's frightening. However, following this he requests that the Animorphs destroy the item that made it possible (by temporarily overwriting his pacifism) because he simply didn't want that happening again.
David, who, whilst a relatively minor character, was one of the most important and memorable characters in the series. Crowning moment? He's the only enemy who truly makes Rachel afraid, by threatening her sisters: "Here's my message, Rachel. I know where you live. You want to threaten my parents? I know where you live."
David turns out to be a huge Magnificent Bastard as well. The first night, he manages to take Tobias, Marco, Ax, and Jake out of action. It doesn't work out that way, and no one dies due to a couple happy accidents - but damn did he come close to killing them all in one night. His final plan is pretty impressive too, though the Animorphs' is even better.
And David managing to kill Saddler, hide the body and replace him flawlessly. It's possibly the most disturbing thing ever done during the series...but it's damned impressive that he was able to pull it off so perfectly.
Ax's CMOA came in the Megamorphs book "In the Time of the Dinosaurs", when, in his natural Andalite form, he KILLS A TYRANNOSAURUS REX that's chasing Marco. This alone might have been enough, but he truly sold it when he was able to convince his human friends, using his usual Sesquipedalian Loquaciousness, that this was a fluke, and that under normal circumstances, "I would lose ninety percent of the time."
And Ax gets one of these approximately every three pages in Back to Before, where he almost single-handedly ends the Yeerk invasion, albeit at great cost. First he escapes his crashed underwater ship alone by capturing and morphing a shark, which he then uses to tear apart the Taxxons chasing him. Ax then breaks into a news station to reveal himself and the Yeerks, then hacks into nearly every American TV channel to broadcast another message to emphasise the truth. Finally he gets onto the parked Blade Ship, with the aid of Jake, Cassie and Rachel who have Dracon beams, and uses it to destroy the orbiting Pool Ship. The best part about the whole thing? It takes them three months to stop the invasion in this timeline, as oppossed to the three years in the main books.
Ax taking down the newly-appointed Visser Two by threatening to drop a nuke on the Yeerks (and his allies' hometown).
By the time we meet Loren in The Andalite Chronicles, she's already taken over the alien spaceship that abducted her.
She later threw a rock at the eventual Visser Three's head, hitting him hard enough to make him bleed. And she was barely a teenager at the time.
She kicked the crap out of Chapman in the same book.
The NEXT time we meet Loren, she totally takes Tobias' revelations in stride despite having no real memory of even having a son and then figures out morphing in roughly thirty seconds.
Keeping her cool in face of harassment from (what she believes to be) three delinquent teen boys should also count.
Marco chewing out Rachel for her screwing up as the team's temporary leader in The Weakness:
Marco: Listen to me, you mall-crawling psycho, we have one hour and ten minutes to get Cassie out of the Yeerk pool. Now, I can come up with a clever plan. I can work all the angles. I can see the perfect solution. But that all takes time. We don't have time, Rachel. We don't have time for clever and subtle. We need reckless, we need impulsive. We need dangerous. We need out-of-your-mind, pure adrenaline, butt-kicking, total out-there insanity.
He stabs his finger at Rachel's face
Marco: We could have used me back at the Community Center. But right now we need you. We have an hour to save your best friend, Jake's girlfriend, and the entire human race. You got us into this, now get us out.
In the same book Marco also manages to kill the Council of Thirteen's inspector by using his cobra morph on the Inspector's very, very fast Garatron host body. The act is described as almost like catching a bullet in mid-air.
Marco: You're fast, Yeerk. I'm faster.
What about how they got into the Yeerk Pool in that book in the first place: stealing a private jet and nosediving it into the roof of a hollow building the Yeerks were using as an entrance tunnel for spacecraft.
Marco's best CMOAs? First, deciding to tell his Dad all about the Animorphs rather than lose another parent, and - after spending almost a whole series coming to grips with probably having to kill his mother someday - freeing her from Visser One. Hell, even Marco's mom gets CMOA then, when she crushes the Yeerk.
In Visser. it's never stated outright that the plan was Marco's, but it seems likely, and he's still enough of a bastard to make Visser One sweat when she calls to ask for his help. Read that again: he makes Visser One, the top military leader of an alien race that is slowly conquering the galaxy, fear for her life because he plays coy about whether or not he'll sabotage her trial. Despite the fact that anything that happens to Visser One could happen to his own mother.Visser-freaking-One calls him a monster. That's pretty Badass right there.
In the last book Jake gets a CMOA by facing down Captain-Prince Asculan, leader of the Andalite force tasked to destroy Earth and the Yeerk forces concentrated on it, despite the Animorphs having just defeated Visser One and captured the Yeerk Pool Ship. He does so in a way that is very polite and diplomatic in wording yet harsh in terms of the subtle barbs directed at the Andalites between the lines of said wording. And said discussion was patched through the Andalite civilian network, trapping Asculan and preventing him from going ahead with Earth's destruction.
Marco also has one here, as the entire time that Jake is going through his CMOA he is narrating in his head what it means in plain english in his own head and to the audience.
Tobias forcing himself to act emotionless and apathetic as Visser Three - who had been masquerading as his last living relative - tells Tobias Elfangor is his father has always been Birdboy's CMOA.
He also walked into that building knowing full well that he was dealing with Visser Three. And he never flinched.
Toby Hamee (Jara's daughter) in #34. Keep in mind that Ax can be rather arrogant when it comes to his Andalite pride.
Toby: "You only ask this [will Aldrea release the body she's possessing] because you don't trust Aldrea. As an Andalite you don't trust anyone who would choose to permanently become Hork-Bajir."
Ax: (after a long pause) <I ask only because it is a logical question.>
Toby: (with "no sincerity whatsoever") "I did not mean to sound suspicious of my Andalite friend."
According to Erek, Cassie's CMOA is performing brain surgery on Ax.
Cassie, sweet, shy, tree-hugging Cassie once made Visser 3 and several Hork-Bajir flee in horror. How? She morphed into a skunk and sprayed them!!! CMoA for Cassie AND for Mother Nature.
This is one-upped when the team holds the secret to removing the smell as their ransom for him to stop his current plan... and then lies about it for a few days to make sure he actually stopped. "Do you think we should tell him it's tomato juice now and not grape?" "Give it a little longer"
Truly Cassie's most epic moment of all took place in Megamorphs #3, when in the midst of all the time travel mayhem it seems that both Jake and Rachel, Cassie's Love Interest and best friend respectively have been killed, and the Animorphs find themselves in the 1930s, confronted by some racist idiot named Davis who used 'a word Tobias wouldn't repeat' and was a general Jerkass to Cassie. Cassie, rather upset over recent events, pleasantly says, "You don't like black people, Mr. Davis? No problem. I can turn white. Watch me." She then proceeds to morph a polar bear, pin the guy to a wall, stick his face in her jaws, and ROAR. Davis, for his part, babbles an apology and continues to apologize long after he's been released. It's a damn good thing Rachel turns up alive again.
Book 19 is an entire CMOA for Cassie: she manages to drive a Yeerk to voluntarily free its host, and does it simply by letting it peek inside her head.
Rachel's threat in the second last book, when Tom is trying to make a deal with the Animorphs. Tom's acting cocky, until Rachel growls, "Don't even listen to him. We grab onto him now, hold onto him for three days and wait until that slug in his head starves to death. Then we have Tom back." This is the first thing said that legitmately scares Tom's Yeerk.
Tom shook his head. "Crazy cousin Rachel. I always knew you were too much for your own good." <Shut up, Yeerk,> Rachel snarled. <You're not my cousin. You're a snail living in my cousin's head.>
Also, Rachel from the final book, when she faces a handful of dangerous morphs for her final battle: "This was my place and my moment and my own perfection. I was no longer afraid. If I had a mouth, I would've smiled. <Well?> I said. No one moved. <Scared?> I asked. No answer. <You should be,> I said, almost laughing."
Tobias got a CMOH here, when he morphs into human so that he can cry.
One of Ax's best moments came in #18, when he tells the Andalite commander who is trying to give him orders (and totally ignoring his human friends) that if he wants Ax to do something, he has to go through Ax's Prince - Jake. The commander is absolutely floored.
Followed immediately by a pretty good one for Jake when the commander doesn't even finish explaining what he wants the Animorphs to do before Jake agrees to do it.
Commander Galuit: <I have need of you to save this planet from the Yeerks. Will you ->
Galuit: <You say yes without knowing what I'm asking.>
Jake: <Will it save the Leerans? Will it keep them free? And most of all, will it hurt the Yeerks?>
Galuit: <Yes to all three. Especially the last. If we save Leera it may turn the tide of the war against the Yeerks.>
Jake: <Then we'll do it.>
Galuit: (Privately to Ax) <I have known worse princes than this one.>
Alloran has a CMOA when he begs Ax to kill him, knowing that his body will otherwise be recaptured by the Yeerks.
Ax and Alloran get a joint CMOA in the final book, when Captain-Prince Asculan flat-out refuses to honor Jake's promises to the Yeerk prisoners. Jake feels defeated, but Ax surprises him: under Andalite law, it is "the right and obligation" of any soldier to challenge the actions of a superior when he feels there's been an injustice. Asculan just laughs at him, because Ax is of insufficient rank to issue a formal challenge. He needs the support of someone of princely rank or higher... so Alloran, who's been Visser Three's host body for years upon years, points out that hey, he's still a War-Prince. The consequences of the challenge failing are that Ax will be exiled and his tail-blade cut off, but he and Alloran still risk it. At this point, Asculan confers with his staff, and ultimately concedes. The best part is that Asculan promotes Ax to prince by a proxy, without even stopping to make him a full warrior first—something not even Ax's legendary brother, Elfangor, could manage. Arbron teased him about it way back in The Andalite Chronicles.
Since he's the enemy of all these CMOA characters Visser Three doesn't get very many of his own. But one moment that stands out is when there was a big complicated Yeerk plan to infest the leaders of the world powers. The Animorphs go through a big complicated plan of their own to stop him...only to discover that it was all a trap and they had ended up right in V-3's clutches.
< By the way, the banquet is tomorrow night. >
Also, how the Animorphs retaliated after they barely escaped from the trap. Outplayed and outmaneuvered, the heroes dispensed with any elegant strategies, morphed into elephants and rhinos, and simply charged through the compound causing as much damage as they could. The banquet, understandably, was canceled. Cassie compared it to preventing a loss in chess by throwing the chessboard across the room.
The best line in the whole series. It's Jake's and the writer's CMoA.
Jake: "Ram the Blade ship."
In #41, when Jake hallucinates a Yeerk-controlled future, Jake speaks with who he believes to be Elfangor (it's actually an aged Tobias in Ax morph):
"The EF [Evolutionist Front] is certainly a force to be reckoned with," I said. <It sounds as though you question our tactics.> "Action is the surest path to change. No question there." <But you would fight them differently? Sabotage and terrorism make you uneasy. You want a better way.> "What I want is to go home." <Too much for you?> Elfangor was an awesome presence. I'd be lying if I said he didn't intimidate me some. But I was a leader, too. I saw the war for Earth as more my fight than his. I wanted to be respectful, but he had made a huge error in this war, and I had to call him on it. "No. I want to go home so I can stop all this from happening in the first place. I can stop the Yeerks without sacrificing my friends, without botching the war, and without stumbling into your brand of terrorisms and half-freedoms. I can stop this before we sacrifice the things we're supposed to be fighting for!" Elfangor laughed. <Victory without sacrifice? You know better than that.> "You don't always have to give up your principles to win. Isn't there always an alternative to sacrifice if you just step back, look at the big picture and -" <You know better than that.> The repetition stung. How had he known I was just talking big? It was like he was inside my mind, rifling through my personal file of fears and mistakes. Now I was angry. "It's all your fault," I shouted suddenly. "I always saw you as a hero, Elfangor. A leader. But the truth is you just couldn't see another way out! You sentenced us to hardship and pain and suffering. We were just kids! You made us question every value we had ever learned! You had no right to heap that weight on us, huge and impossible. You used us!" <That's funny coming from you, Jake. Let me guess what comes next. You didn't ask for this, right? You didn't ask to be the leader. You never wanted to make the tough calls, decide how to put your friends in harm's way. You're blameless. The role was thrust upon you. Well, I don't buy it, Jake. Every choice is yours. Always has been.>
If David gets a Crowning Moment, Tom (/his Yeerk) does too:
"You appear to be experiencing some engine trouble, Visser," Tom said, gloating. <The Empire will hunt you down and kill you for this, you do understand that, I hope?> Visser One asked. "Oh, I doubt it," replied Tom cheerfully. "The Andalite fleet is rather close by. It's possible that I misled you on that part." He was all but giggling.
Alloran gets one in The Andalite Chronicles that is also a rare CMOH, considering that at this point, he was a General Ripper and treated the humans with contempt. When Loren explains that her father was a Vietnam Veteran and that he came home crazy, Chapman mocks her father, saying he was weak. Alloran asks Chapman if he fought in a war. Chapman answers "no", then Alloran tells him to shut the hell up because he has no idea what horrors soldiers go through.
Tobias has a CMoA that is nearly series-long, but never focused on. Whenever the group directly engages Visser Three, there is almost always a line about Tobias charging him- while in his default hawk form. A teenager trapped as a bird of prey attacking a trained killer in an Andalite body head-on. The CMOA comes from the fact that Tobias has a tendency to win these duels.
Another one for Rachel during the David trilogy: while in rat form, she chews her own tail off to stop his attempt at Taking You with Me.
Practically everything that Elfangor did before and after the series began was a CMOA from his first adventure that changed history to his death where he refused to let a world go down in flames due to some old code and die fighting his nemesis than bowing, all amazing, simply amazing
Rachel manages to morph grizzly bear to tunnel her way out of a Kronosaurus in In the Time of Dinosaurs.
Most of Visser Three's morphs. Eating Elfangor in one bite, right at the start of the first book? Check. Something that is essentially made of fire? Check, if impractical. At least two large creatures that fire deadly-looking projectiles? But of course!
In #38 The Arrival, The Animorphs really show the Andalites who's boss. For those curious, that included showing up with the intention of being treated as equals, storming out upon being denied that request, overpowering the Andalites when they try to force them to stay, making it clear that Jake is in charge of the entire operation, and later pulling a Batman Gambit to top it all off.
Of particular note is this exchange:
Gonrod: Are all humans as arrogant as you? You dare to make demands of the highest-ranking Andalite within light years?
Jake: Huh. So, your rank is 'Commander' and you're the highest-ranking Andalite within light years?
Ax: A Commander is typically in charge of a single ship. A single *small* ship.
Arbat: (cracking up) There goes our plan to bluff the enemy into thinking we have superior numbers.
In The Hidden, a buffalo acquires the ability to morph. Through a series of accidents and reflexes, it lays dying, then acquires and morphs Visser three's host, then goes tail-to-tail with Visser three and comes out ahead. It makes Alloran, and anybody whose ever fought the visser, look bad.
In the last book, Rachel hides on the Blade Ship, morphs grizzly, and manages to kill pretty much everyone on the bridge. And for the first time in the series, the Yeerks don't use "Andalite bandit."
Rachel: <That's right, Yeerk. Animorph.>
Of course, since Ax actually *is* an Andalite, he gets the chance to make badass responses like this all the way through the series:
Megamorphs #1: Marco and Ax escape captivity on the Blade Ship by jumping out of it into outer space, at which point Marco demorphs out of his Gorilla morph and into an osprey just in time to save himself from falling to his death. Bonus points for pulling this off while scared out of his mind, despite the fact that morphing typically requires concentration.
This is sort of a CMOA by proxy for Jake:
Naomi: Okay, fine, Eva. You've been in this war. You know the enemy. And you're old enough to drive. You should be the leader.
Eva: No, I shouldn't. Yes, I know the enemy. But there's only one person in the galaxy that Visser Three is afraid of, and that's Jake.
Tom - the real Tom - gets one in the very first book, when the Animorphs manage to briefly free him and a bunch of other hosts. When he gets cornered by some Taxxons, he tries to fight them off, and then he charges at Visser 3 - currently morphed as some enormous, monstrous creature - completely unarmed. A teenage boy attacks a giant alien monster with just his fists. Naturally, he achieves absolutely nothing with this, but still, it's a pretty awesome thing to do.
Although it becomes Frige Horror/Tear Jerker when you realize that he may have been trying to kill himself before he could be reinfested.
Alloran in the final book, after Visser One departs his cranium. Aware of his reputation as the General Ripper who tried to euthanise the Hork-Bajir species, as well as the only Andalite unlucky enough to be infested by a Yeerk, he gives a Patrick Stewart Speech about how he's aware those will mar his reputation for the rest of his life...and he simply doesn't give a shit, because he's free now. He curls his tail of his own accord, and the ability to control his own body again makes him laugh and cry out in euphoria. If Andalite arms weren't so weak, he'd probably ask for a high five.