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.
Worth noting is Jigoku-hen plays with the event as much as possible, as Char Aznablenever intended to drop Axis; Full Frontal is the one doing it. Essentially, Char fooled the entire Neo Zeon faction into taking advantage of the asteroid so he could use it as a Singularity Point in an attempt to fix the dimensional disruptions occurring in the Earth Sphere and break them free of the Time Prison. Sure, this setup counts as Superdickery, but the fact Char doesn't neglect what he said in Z regarding not allowing the Black History from occurring is a sign his Character Development is consistent and not Retconned by the events of Char's Counterattack.
Taken to further heights as the Colony Drop continues. Char reveals his Xanatos Gambit: in the event Axis cannot be physically stopped by Z-BLUE, he had Athrun Zala and Lunamaria Hawke build devices fitted with GN Drives across the globe and link them together via the Quantum System in order draw on the willpower of all mankind as a physical force, holding Axis back long enough for Traiya Scott to activate a mechanism involving Fold Quartz Crystals, Z-Chips and the remains of the Insaraum ZONE System to teleport the asteroid to a safe location. It works.
As a final bit, in Char's Counterattack, just before the Psycoframe in the Nu Gundam overloads, Char incredulously wonders "Is this the light of the human heart?" In Jigoku-hen, this very question becomes a Meaningful Echo, a rallying cry for Z-BLUE, with Char answering his own question as "the power of hope for the future".
The Invaders reappear in Jigoku-hen out of blue, taking Ryouma by surprise and eating the Black Getter. Ryouma is taken to a point between dimensions, the same place seen in the last episode of Getter Robo Armageddon, and greeted by another incarnation of himself, who tells him the truth about fighting the Invaders for eternity. Reinvigorated, Ryouma reawakens, bursts out of the Invader's stomach ready to fight them all; at the same time, Hayato and Benkei arrive with the Shin Getter Robo in tow.
Baron Ashura is Driven to Suicide and the Shin Mazinger ending is re-enacted.Kouji Kabuto becomes slim pickings for The Emperor of Darkness as the latter decimates the Mazinger, but Kouji gives one last effort with a Big Bang Punch. It doesn't work and the God Scrander is destroyed, with the Mazinger falling and powering down. Cue Zeus appearing to give Kouji a hand.
As a TakeThat, the Anti-Spiral yells at Shinji, when he says he isn't going to listen to what the Anti-Spiral has to say, that Shinji is averting his eyes from reality. Shinji retorts that Anti-Spiral is the one doing that and tells him he shouldn't run away.
The final DLC side stage. Ultimate Battle. In the short while before going to face the Anti Spiral, AG says he's compiled a final training program for everyone to get ready for the battle. It turns to be your entire roster minus secret characters, with Super Galaxy Gurren Lagann as the battleship...vs EVERY major boss character not named Anti Spiral,(except Big Venus because she instakills her opponents which wouldn't be fair, or Char, because he's in your roster at that point). Gadlight, Frontal, Haman, Hades, Izumo and Mikage, Gauron, etc. With lessened HP to keep things balanced. And everyone starts at 130 will. Go nuts. Not only is it a cool fight, but gamewise it also means you can use the strongest characters and fight the final bosses whenever you feel like without having to replay the whole story. If any DLC is worth it, it's this.
If the Unit 03 debacle happens, Shinji plans to attack Nerv HQ as in the film. Whereas some of your more lawful members try to talk him out of it while others think that's too excessive even for Gendo, Ryouma essentially says "Let him kill the bastard." and lets him go on his way and is surprisingly enough backed up by Roger Smith, who while not one to endorse needless violence has decided Gendo is no longer to be trusted.
This partially serves as a Call Back to Kira's more agressive days back in Gundam SEED, where he often made use of the Aile Strike's beam sabers. Shinn's shocked by Kira showing such a side (being used to his GSD attitude).
The final stage, with the glory that is the Tengen Toppa Gurren Lagann. The fact that this thing is playable is amazing enough, but the rest of Z-Blue go size infinity to join it in kicking Anti-Spiral ass.
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. The later is even a bit of a Crowning Moment of Funny due to how unexpected it was for Ribbons.
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".
With Jigoku-hen announced, Getter Robo Armageddon, Gunbuster and Tengen Toppa Gurren Lagann will be in the same game, making this potentially one of the most Hot-Blooded SRW installments...at least until other series are included in the yet-to-be-released Jigoku-hen sequel.
The actual Tengen Toppa Gurren Lagannwill be a playable unit, with its strongest attack turning into the Super Tengen Toppa Gurren Lagann. It also features perhaps one of the most beautiful deliveries of the Giga Drill Break ever, with highly detailed and well animated visuals backed by some of Gurren Lagann's most iconic, Manly Tears-inducing imagery. This has led to the additional fandom joke that the rest of the budget got blown on the Tengen Toppa Gurren Lagann.
Then, they decided to top this by dropping in Diebuster for Tengoku-Hen.