When Master Xehanort commits Grand Theft Me on Terra and emerges as the young Xehanort, he begins to walk away when Terra's armor reforms and conjures a barrier of light around the arena. First, Theme Music Power-Up because the battle theme is Raged Awakened, the theme when fighting the Lingering Sentiment. Second, Terra uses the Power Of Hate to become Animated Armor and battle Xehanort in his own body. Third, you get to take control That One Boss to deal a beatdown on the main antagonist of the series who up until now has been The Unfought. Fourth, for once the barrier around the arena isn't the boss's, it's Terra's — he's making sure Xehanort has nowhere to run. Fifth and finally, it's Xehanort. Not Ansem, not Xemnas, not Master Xehanort. After dealing with his alter-egos for five games before, you finally face Xehanort himself, and he's a Lightning BruiserMagic Knight with access to every single attack you've come to rely on during the game.
Ventus uses Heroic Willpower to unfreeze himself to protect Aqua from Vanitas. Then Vanitas unmasks himself and merges with Ventus, leading to a Battle in the Center of the Mind on a corrupted Dive to the Heart showing Vanitas opposite Ventus. Ventus fights knowing full well that if he destroys the X-Blade, both of them will lose their hearts. But as he says, "anything to save Terra and Aqua". And the fight ends with the two using their keyblades to fire a giant Beam-O-War, Ventus overpowering Vanitas to charge up his Finishing Move and deal the final blow.
As Aqua and Mickey encounter a spacey Ven, the former approaches him to ask what is going on. Mickey instantly realizes there's something fishy about the situation, so when "Ven" reveals himself to be Vanitas possessing the poor kid and immediately tries to stab Aqua with the χ-Blade, the King jumps in, blocking in with his Star Seeker when the χ-Blade was millimeters from Aqua's heart! It's right there you know King Mickey took one of his many levels inBadass.
Also a crowning moment for Vanitas, in which he shows that he is not a stupid villain. This is the second time that he's attacked Aqua without warning, because he's faced her twice in the past and she won. He's the only villain smart enough to use sneak attacks.
And of course, there's the True Final Boss. You get to fight Xehanort again as Aqua, and he's just as powerful as when you fought him with Terra. Then he busts out the Guardian. And Aqua still kicks his ass.
Seeing Cinderella's wicked stepfamily get what's coming to them.
Scrooge McDuck talked back to an Unversed. Sure, he's badass in his canon, but that still takes balls to do that while unarmed. All because he thought the Unversed may have been after his munny, of course. That's right, when faced with possible death, Scrooge only cares for the safety of his well-earned munny. Now that is Badass.
AnotherCool Old Guy from Disney has a great moment in Ven's story...
Ven: "Mister, get inside! It's not safe out here!"
Merlin: "Oh, ordering me about—now that's unsafe!".
Aqua creates Castle Oblivion. This place was the whole mysterious setting of Chain of Memories and it's almost a mindfuck when you learn that it was Aqua who created it. She modified a whole world!
Aqua, gameplay-wise, she canonically beats both of the other main character's final bosses. Hell, she took on Ventus's twice! And she beat the Memetic Badass, Vanitas, three times, with the last one being when he is in possession of the ultimate weapon!
Vanitas has some impressive Crowning Dialogue of Awesome, though some of it may also count as Nightmare Fuel. Among the greatest examples for him is this: "In that case, I'll choke the life out of your friends. Then let's see how long you play the pacifist."
The scene where Terra is watching his home world being destroyed was pretty freakin' sweet. Not because the world itself was being destroyed (that's sad), but with the way the camera shook while he was just watching made the scene look intense.
After Ventus is frozen solid by Xehanort, he is dropped down to where Aqua is, who then has to fight Braig, and all he can do is watch. Then Aqua gets hit by Vanitas' sneak attack, and Ventus DEFROSTS HIMSELF WITH HIS ANGER to fight him.
"You may be my master but, I will not let you hurt my friend!" was an epic one for Terra, even if it turned out prettybadlyforhim.
Vanitas forging the X-Blade, after some great gloating too.
A villainous example has to be when Braig, pissed that he got scarred from a fight that Xehanort set up, starts shooting at him. How does Xehanort take this? He just sits back and lets the bullets hit his shield. And then, when Braig gets in close range, Xehanort just summons his Keyblade right to his throat, causing Braig to back down his aggressiveness.
Xehanort's face during all this. It looks like he's just laughing off all his pitiful attempts to do any damage.
Another villainous example: when Vanitas explains how he creates the Unversed, he casually creates a whole bunch of Unversed, including Floods, Tank Topplers, and a Trinity Armor, and then just as casually dismisses and reabsorbs all of them. The first time through, those guys could beat you right up, but he doesn't even acknowledge it as even a thing.
One for Aqua that's not even in the story. When the Bonus Boss Mysterious Figure appears before Ventus and Terra and summons his laser blades, the two of them summon their keyblades with a surprised look on their faces. When the same thing happens to Aqua, she just calmly summons her keyblade like it's no big thing with a "let's do this!" look on her face.