Delivering the ZEUTH vs ZEUTH scenario, built up for the entire first act of Z, while making the scenario completely controllable by the player (resulting in a very high HSQ when the player realizes this is actually going to happenandit's fully playable).
Second Super Robot Wars Z: Hakai-Hen
In Scenario 18-A of the third route split, during a concert in the Macross Frontier storyline, Sheryl Nome sings "Iteza Gogo Kuji Don't be late", which pumps up ZEXIS so much all allied pilots' Will instantly shoot to 130. After defeating the initial enemies, Baron Ashura arrives with some MechanicalBeasts; this causes Ranka Lee to take the stage and sing her song "What 'bout my star?", pumping Simon and Kamina up even further, to the point where the latter debuts the Gurren Lagann's most famous attack, the "Giga Drill Break", nearly obliterating the Mechanical Beast Toros D-7 with it.
Lelouch Lamperouge gets one, not as Zero, but as himself as a normal student. Terrorists have a large portion of the student body held hostage, during the heart hat event, along with Lelouch. What does he do? Distract them long enough for everyone to get away, leaving him alone with a bunch of angry terrorists. He then gets saved when several members of ZEXIS burst in from the window.
In another moment, this time as Zero, when Esther Elhaasis turned into a Dimensional Beast, Lelouch takes it upon himself to stop her (either launching from the Ikaruga if he is not deployed or moving himself in Esther's path if he is deployed in the Shinkirou), placing a Geass command on her to stop attacking. Made more awesome because Lelouch didn't even think of what he was doing; he's pretty much just trying to stop something over fifty times heavier than him from hurting his allies and friends, and is lucky enough to accidentally Geass her successfully.
Elgan gets another one: since he is the Alternate Universe version of The Edel Bernal, he fears he may lose control like his Evil Counterpart did upon learning about the Black Knowledge, thus placed a clause in the Earth Federation's charter when he was the Secretary-General of the United Nations. That clause states no matter what the Federation does, ZEXIS will have supreme authority to police the Earth if it is reformed. Neither the A-LAWS or Organization of Zodiac can overrule this. The best of this is he did this while he was being manipulated by Ribbons Almark.
The debut of Dynamite Explosion in scenario 37. Not only does it drive Aim Liard away, but it also sends a wave of Vajra retreating. ZEXIS is surprised by this turn of events (as they were surrounded by the Vajra and Mobile Dolls) and applauds the talents of Basara Nekki. To top it off, Basara manages to emotionally move Chirico Cuvie, who SMILES in response to the song.
Ribbons: Amuro Ray, THIS is the difference between our powers!
When Schneizel el Britannia reveals Zero's identity, the Black Knights are considerably concerned with the revelation. Granted, they just witnessed Suzaku nuke Tokyo with FLEIJA and are furious at Zero. Of all the people to try and reason with the Black Knights, Chang Wufei is the most vocal, calling out the stupidity of Ohgi Kaname and the other Black Knights. He goes on to list all of the things Zero has promised to do and followed up on, including the fact that Zero having the power of Geass is irrelevant, given that half of ZEXIS possess supernatural powers of their own. Furthermore, Wufei reminds Ohgi and the others that Zero is the supreme commander of ZEXIS, meaning if the Black Knights want to betray Lelouch, they have to win over their ZEXIS colleagues (who are doubtful of Schneizel's intentions). Wufei adds that they're obviously confused and emotional following the nuking and are just looking for a convenient scapegoat, which Schneizel gladly provided with his accusations. He rounds it out by saying if the Black Knights want to fulfill their dream, Zero is their best bet to achieving it. Sadly, this piece of dialogue only occurs in the normal route path where the Black Knights go ahead and betray Lelouch, but considering Wufei is normally a Butt Monkey in the franchise, particularly his frequency of joining enemy factions as per Mobile Suit Gundam Wing Endless Waltz, this is without a doubt the single greatest thing he's done yet (until Super Robot Wars L). Also doubles as Shown Their Work for Banpresto.note In the backstory of the Gundam Wing manga Episode Zero, Wufei was more of a scholar than a fighter. It was his wife's death that caused him to take up arms against OZ.
Note the above paragraph mentions this scene only triggers in the normal route. Well, if you fulfilled the correct requirements, once you get to the point of Schneizel's reveal, it's up to the player to decide whether or not ZEXIS rebuffs Schneizel and continues to trust Zero! Basically, Banpresto pulled another Gundam Seed Destiny level of Fix Fic and the biggest Wall Banger of Code Geass can be completely averted!
Apollo(nius): "Ba'al... you really are beasts. You who cannot fathom the love and compassion of Man do not deserve to exist beneath the Sun. Ba'al, the Mechanical Angel Aquarion hereby refutes your existence! Behold! The power of mankind... and the power of life!"
Scenario 54, full stop. ZEXIS is facing Nia in her Anti-Spiral unit and things are looking grim, as she's about to drop the Cathedral Lazengann on Earth when suddenly the Shin Dragon punches a hole through space/time and not only does it appear next to Nia, but it brings along some allies you thought sacrificed themselves earlier in the game. That's right, folks: Rand and Setsuko are back!
The IF route version is even better: Nia's about to drop the moon, but Holland Novak (who's been absent all game) appears. Not much help, except Holland can't even finish his Big Damn Heroes speech before Gino Weinburg and Anya Alstreim appear as friendly reinforcements, deciding they'll stick with their friend Suzaku after all. Next is Ozma Lee and Luca Angelloni, finally catching up with the Frontier fleet after their adventures looking for Space Whales. Finally, the Shin Dragon arrives with Rand and Setsuko in tow. That's four simultaneous Big Damn Heroes at once.
NeoSaint has a Let's Play for Saisei-hen with a number of "Arranged Battles": movies made by editing the attack animations into coherent battle scenes. They begin with simple beatdowns on the bosses, but as the game progresses, get better and more detailed, telling the story of each battle in their own way. By the time the Shin Mazingerbattle against Dr. Hell, he's actually hacking the game and re-editing the game map to make attacks that are impossible to perform in the game (such as Tetsujin #28 and Dai-Guardthrowing Missile Mechanical Beasts back at the villains). The finale is particularly epic, with the Rocket Punch 102 Rapid fists (Dancougar Nova and the Sol Gravion get their fists in edgewise), ending with a "Big Bang Punch"-"Giga Drill Break" cross-up.
Best of all, Lelouch himself is leading the charge from the Sol Gravion!
The Gundam 00 ending features nearly every single Gundam unit, each with some screen time and it all culminates in Ribbons vs. Amuro and Setsuna, with two endings: either Ribbons hijacks the Nu Gundam, forcing Setsuna and Amuro to take him on in the Exia and the Tallgeese or Celestial Being keeps him from getting away at all and takes him down with the Dancougar Nova.
Zxyu0369 also makes good arrangements, the best one being ZeroRequiem, with ZEXIS vs Emperor Lelouch vi Britannia. Knowing the characters, the battle greatly delivers on tension and drama, as both sides are fighting each other for peace through different ideals and methods. Duels include Kallen vs. Suzaku, Heero Yuy vs. Zechs Marquise, Setsuna vs. Mr. Bushido, and ultimately many members of ZEXIS against Lelouch himself.
""Flash!! The End of Evolution!" is another fantastic battle that focuses on ZEXIS against the Invaders. Whether it be in the middle of the video where Kira, Athrun Zala, and Simon among others blasting the hell out of the Invader armies or the end of the battle where Athrun, the Big O, God Gravion, and the Getter Team are charging and unleashing their strongest attacks against the boss, utterly decimating it, everything is done to the tune of "HEATS".