Adding spice to the moment above: for the first time in the series, Zero has now brought the long-running Robot War to an end. An Anti Anti Christ he is, indeed.
Not only that, but Zero has finally found the answer to the question that's been screaming in his head for a century. " What am I fighting for?" Iris's death is no longer in vain. And Zero goes out in a blaze of glory so bright that even the heavens must bow their heads.
Really, everything about the lead-up to that battle screams AWESOME. Zero gave us two series' worth of reasons to like him, and in turn it also gave us only two games (plus a drama track) to do the exact opposite with Weil. The bastard's just been asking for it, and adding the elements above, it gave us a Grand Finale truly worthy of a Mega Man series. And, aside from the series' biggest Tear Jerker, There Was Much Rejoicing, among fans and in-game characters alike.
Not quite as good, but still beautiful to watch, is Harpuia coming across an unconscious and almost dead Zero in the desert and having a "to live or die" moment.
And there's also the ending in the first game, where he calls Copy X weak and tells him that the real X is strong because he is fighting for something.
And in the third game, after Ciel's attempts at diplomacy have failed, Zero tells her that she did what she could but, "What happens next is my job." Cue ass kicking.
Zero: We're only Reploids designed for war. It's not our place to change the world. That's up to humans like Ciel and Neige. As Reploids, we can only lend strength to those we trust.
Craft: Trust? And just who should I be trusting? The humans that do nothing while their world falls apart? The humans that fear us, their own creations? Or the humans that try to conquer the world? We fight each other for them!? This world screams out in pain under them... Why should I trust anyone? How can you trust them? How can you fight?
Zero: I made a promise to a friend I intend to keep. To someone who believed harmony between human and Reploid was possible. I trust that friend. And I trust the humans that friend trusts...
Your mileage may vary indeed. Suddenly stating that Reploids shouldn't try and change the world completely undermines the purpose of reploids. Still, the intended effect could be accomplished by saying that soldiers should lend their strength to the ones they trust: true leaders like X and Ciel.
Zero shouldn't have all the glory. In Z3, there's that part where the resistance base gets Brainwashed by Weil using Omega, and Zero is clearly in a conflict as to how to protect Ciel without cutting his companions to ribbons. Cue X appearing and using his awesome Cyber Elf powers to knock out the entire freakin' base, and then he makes the whole base immune, all that while he's weak and fading away from using too much energy/staying too long without his body. (Of course, this display probably contributed to that).
Zero: You're just going to abandon her? She put her life on the line to stop the fight and save you and your Settlement!
NPC: What of it!? If we save her, we might get attacked again!
Zero: Look at you all cowering in fear. You're no different than the humans in Neo Arcadia...
NPC: H-how dare you!
Zero: If you're going to be like that, why even put your lives at stake to leave Neo Arcadia in the first place?
Seems like nothing came out of Zero's verbal assault, did it? Until this happens:
NPC: We can't do anything to save Neige. We humans aren't as strong as you Reploids. But you were right. If we abandon Neige, this whole Settlement means nothing. From the moment we all decided to live free of Weil's rule, Neige has helped us too many times to count. We don't have the right to ask you this, but... Please save Neige for us. If you really aren't like Weil and the others, please lend us your strength!
The hostility of the humans towards the Reploids has ended with those words. And that's where peace has finally started to resurface after a VERY long time.
What about at the beginning of the very first game? Zero's been asleep for a hundred and some years, has lost most of his memory, lacks the ability to charge his buster, and is lacking his Z-saber. When they find him, they have no idea of any of these things except for the first. Ciel's Cyber-Elf, on her own, gives up her life to awaken him. Nothing happens for a second. And then a bright light fills the room and suddenly (to every SNES gamer's happiness), guitars and drums are cued to a remixed version of Zero's Original theme. The epic one that was used when he shot a Ride Armor's arm off.
Ciel: Zero... has been resurrected.
Ciel: Zero? Help me. Please...
Zero: [shifts to a fighting stance]
All through the stage you are just TEARING a path through the enemies with an unchargeable buster. Music still going and making you feel like you're a god of destruction. Then comes the golem, which Ciel claims can't be defeated with just a buster. You take out a good portion of its health before Cyber Elf X appears, gives you the Z-saber back, and you destroy the Golem with a single slash. Even without his memories, Zero is, and always will be, a badass.
To further up the already-ludicrous badass level in that scene: you can opt to forgo using the Z-Saber after the cutscene and continue using the Buster to defeat the Golem. Um, care to tell Zero he can't do that again, Ciel? I don't think he quite heard you over all the badass.
Furthering his badassery is the fact that he doesn't even have a Buster at all... The Complete Works Artbook reveals that he just picked up the worthless pea-shooter Milan was using, and it was upgraded on contact to shoot buster-pellets instead of 9mm rounds.
Talking about Phantom, remember that moment in Mega Man Zero 1 when he tried to take out Zero by sacrificing himself?
When Weil gloats about how a Reploid could never image the enjoyment of controlling every Reploid on Earth, Zero's Shut Up, Hannibal! is to say that he doubts most sensible humans could image it either.
Neige gets one of these when she tells Weil that she'd rather laugh death in the face than endure a living death under his rule, before giving him the middle finger with a flashbang. Who says Reploids have to get all the glory?
Neige: If the only other choice is a living death under you... Then I'd rather choose to laugh death in the face and face it with dignity! Zero! Now! *throws flashbang*
Ciel: Thank you, Zero. If our defense line was broken, this Base wouldn't last long... Still, I can't believe you wiped out such a large number of enemies... You are truly a legendary hero.
After Zero defeats Copy X, he fell onto a desert and fainted. When he woke up, a huge army of Pantheons appears behind him. Cue Zero's Badass Creed:
Zero: I'll do what you want... Rest for a while. I will handle it, you can count on me. I won't stop! If an enemy appears... I'll terminate it.
And then he proceeded to kick mass amounts of ass... and survived for one year to the intro stage of Zero 2.
A meta one for some players out there: ever get so depressed about the fate of Cyber Elves that you resign to get through the games without ever using one (and thus ending it's poor little life)? It will mean having to go through some of the most Nintendo Hard games out of Capcom since the class series! It is possible though, and you will feel like a badass making a joke out of each of the final bosses with that miniscule little life bar.