Promotional art for Mega Man Zero 3. Background, clockwise from the top: Weil, Weil's Numbers (eight), and Omega. Foreground, left to right: Zero and Ciel.
Another entry into Capcom's popular flagship series Mega Man, although it is a more direct sequel to Mega Man X and is even Darker and Edgier than the latter series. The first game was released for the Game Boy Advance in 2002 and continues the story of Zero, the partner and best friend of the latter series' protagonist.A century after the Elf Wars, themselves an unknown number of years after the X series, Zero awakens to find the world is still not at peace and Reploids are being hunted by Neo Arcadia, a utopia for humans and Reploids Gone Horribly Wrong. Ciel, a human scientist who leads the Reploid resistance, revives Zero and asks for his help in stopping Neo Arcadia and to bring peace between humans and Reploids.The series lasted for four games and spawned a sequel series, Mega Man ZX, which currently stands at two installments. A Compilation Re-release of the entire saga has also been released for the Nintendo DS.Keep in mind that many of the following tropes contain spoilers. You've been warned.See the series's character page for more info.Vote on the best game in the series here.
All Your Powers Combined: The "mimic elf" in the fourth game; it has 21 abilities that were adapted from cyber-elves from the previous games. And, in Ultimate Mode, nearly all these abilities can be used without a single penalty, and, true to the trope, all at the same time.
Sometimes the Ultimate Mode can backfire, since the constant stream of elemental shots can obscure your view, and can trigger an enemy's invincibility frames just before you unleash a much more effective strike. And because of how the abilities stack, having all three elemental shots active is the only way to use the increased defense. However, the health boosts do NOT stack (although you DO get the random health pickup drops). It isn't much of a penalty, since the highest health power up is the equivalent of the max health bar from previous games.
A Million is a Statistic: In Zero 4, Craft fired the Kill Sat Ragnarok at Neo Arcadia, trying to kill the Dr. Weil. The attack, according to the manual, claimed 20,000,000 deaths of innocents. Yet the intended target ironically survives.
Earlier, in the third game, the missile containing Omega successfully hit a whole city block, claiming thousands of lives.
Androids Are People, Too: Played with. The reploids in Neo Arcadia are treated as second class citizens, except for the higher-ups in its governing body as well as the reploid army. However it's implied that they were treated the same as humans when X was still the ruler, seeing as it's his dream.
Antlion Monster: The Sand Jaws enemies lie in a middle of a quicksand pit, waiting for the player; they'll then bite the player for slow but continuous pain.
Arc Welding: Unlike the twoseries that preceded it, every Zero game has a different Big Bad. This is shot down by Zero 3 and Zero 4, wherein the Big Bad those two games have in common, Dr. Weil, can be easily marked responsible for the events of the previous two, making him the Big Bad for the entire Zero series.
Art Evolution/Shift: In part because the new character designer for the series, Toru Nakayama.
Also, much of the concept art and character mugshots in Z1 are incredibly sketchy compared to the cleaned up style of all the subsequent games. Zero also looks gradually more masculine as the series goes on.
Also in Zero 1, when you approach Ciel to save or start a mission:
Ciel: "What's now?"
In Zero 2, Ciel's computer asks: "Do you want to know?" Ciel also constantly uses the word "subsequent" in reference to her new form of energy, when the obvious intended meaning is "substitute."
Some of the boss names suffered, especially Tretista Kelverian. As he's a Cerberus-themed character, his name is clearly supposed to be Tritestanote Latin for "three heads"Cerberian. Indeed, the names are mangled to the point where they sound like they should make sense, you just can't point out how, exactly.
The Zero 3 database listed Phantom as the "Evil Dark Lord". It should have been "Shadow General". The other Guardians also get odd-sounding prefixes, but at least those fit their characteristics.
Boss Warning Siren: A WARNING sign flashes on the screen just like in the Mega Man X series, only this time it appears after the boss' monologue, if any.
Bottomless Pit Rescue Service: In 3 with the Cyber Elves, but only once per Elf... Unless when you upgrade them into Satellite-Elves, which makes them last forever and thus, you could not die from pits. Also in 4, where the nature of the special elf also gives the same result as above.
Bowdlerise: A very mild version. In order to keep an E rating, the blood sprays were edited out of the American release. Arguably for the better, since even the robots bled in the original. Presumable it's supposed to be some kind of oil.
And then for Zero Collection for the DS, they're inexplicably left in.
but in return some of the revised translated script kept the words death, die and kill from being used too often.
Bragging Rights Reward: Getting S ranks. A rank is sufficient to get any of the unlockable content, and S rank is damn hard to achieve in some levels, especially if you're playing on Hard Mode.
Subverted in 2 and 3, where you got a new technique (see Power Copying) that made the game easier if you ranked A or higher. Played straight in 4 where getting the power had nothing to do with rank.
Not to mention the mini games from Zero 3, including the ones you got by getting 100 points on each level, aka finishing quickly, not being hit more than once per level, destroy as many mooks as you see, not using any Cyber Elves, not falling to bottomless pits/spikes of doom, and not failing the mission by going to Cyberspace. Simple, right?
Also, Zero believes that there's still good humans to bring peace.
Brought to You by the Letter "S": All bosses for the first three games have the Greek letter Omega as their symbol (due to it being the symbol of Neo Arcadia); the fourth game replaces this with W/V. Zero's own signature Z is gone, for obvious reasons, but concept art for the Z-Knuckle shows that the chips representing the weapon retains the iconic symbol.
The 4 Guardians have an X on their chest, as well as on their back.
Bus Full of Innocents: Area Z-3079, a whole city block, the target of a missile by Dr. Weil with Omega inside, who was sent to capture the Dark Elf spotted inside the area. Needless to say, Zero fails the mission, with hundreds of innocents killed.
There's also one in the final game, which is all of Neo Arcadia itself! Not part of the Big Bad's plans; in fact, the target of the attack was Dr. Weil himself, by his Bastard Understudy.
But Thou Must: In Zero 2, refusing to help Elpizo with Operation Righteous Strike near the beginning of the game simply ends the conversation. However, there is literally nothing else to do other than roll around the base, which Elpizo snarkily lampshades if you initially refuse. Later on, once the operation commences, the two navigators will take turns begging you to follow Elpizo until you accept.
Color-Coded Elements: Fire is associated with Red, Water/Ice is associated with Blue, Electric/Wind is associated with both Green and Yellow, and Non-elemental is associated with Purple. This is later brought out into the ZX series.
Continuing Is Painful: In Zero 2, dying knocks three points off of your mission score. This is perfectly fair. However, dying also removes any points you'd accumulated from destroying enemies. God forbid you try to perfect-run the final stage.
Continuity Nod: In Zero 1, Copy X's arsenal is chock full of these. He has an offensive Slide Attack similar to the Charge Kick from Mega Man 5, and his elemental attacks are basically the Shotgun Ice, Fire Wave and Electric Spark weapons from the original Mega Man X game.
Phoenix Magnion in Zero 2, being an illusion specialist, is able to draw from Zero's memories images of his old foes from the Mega Man X series to torment him. Vile, Agile, Bit and Colonel pop up for some tag team fun.
In Zero 4, Dr. Weil summons the bosses from 3 to assault the hero.
The final mission in the first game takes place in an orbital elevator, like the Jacob from Mega Man X 8. While X8 came out after Z1, this arguably brings the post-X5 series out of Canon Discontinuity.
In the first game, you encounter Repliforce (from X4) submarines.
In the Hibernation Chamber level of Zero 4 there are various iron pipes that Zero can use with the Z-knuckle. Zero used an iron pipe against Sigma back when he first awoke from hibernation in Mega Man X.
A Lower Deck Drama Track features Alouette wandering the Resistance base in search of a name for the Baby Elves. Zero refuses to even attempt naming them, which ticks Alouette off. In Zero 4, if you refuse to use Alouette's name for your new elf, you are not allowed to name it yourself and Zero has to wander the trailer looking for names.
One of Andrew's Rambling Old Man Monologues is about the time one of his students gave him a three-leaf clover after failing to find a four-leaf clover. Later on, Brise states that clovers used to remind her grandmother of her teacher.
Similarly, in Zero 3 (again), between the first boss set (four of Eight Gentle Judges) and the third set (other four judges), the second set (3 bosses) and the one after the Judges are remakes of four bosses from Zero 1: Blizzack Stagroff R, Hanumachine R, Anubistep Necromanses V (the Zero 1 version was Anubistep Necromanses the Third), and Copy X Mk. 2.
Dynamic Difficulty: If you have A or S rank when you're fighting bosses, they'll have a special move. The Guardians will have a Desperation Attack that makes them invincible during execution. In Zero 4, if the stage's weather is compatible with the boss (indicated with highlighted lines near the stage icon), the boss and the stage will be harder.
Earn Your Fun: The "Ultimate Mode". To elaborate, you'll start the game with all of the Cyber-elves abilities activated without any penalty. It also has good stats, and you can do instant charged attacks using button commands. In Zero 3, some of the upgrade chips are also available from the start, including the Infinity Plus One Boots. That's worth all the effort of Gotta Catch Them All (specifically, the Cyber-Elves).
The Mega Man Zero Collection subverts this with Easy Scenario, which automaticly starts the games in their "Ultimate Modes", but they have to be played in sequental order.
Earn Your Happy Ending: The peaceful era after hundreds of years of war has finally come, and the enmity is finally dissolved between humans and Reploids by the two sides working together. However, it's subverted in that, those who really fought hard for such peace, X and Zero, sadly never had the chance to see it (at least, not on the earthly plane).
Emergency Energy Tank: Some Cyber-elves can function as this; some heal directly, some give extra lives, some become Sub-Tanks, etc.
Fan Nickname: The series is often referred to as the "Second Maverick Wars", with Mega Man X then referred to as the first.
Fantastic Racism: As a result of the discrimination, most mass produced reploids have No Name Given, being simply called by their designated serial numbers, like TK-31 or HE-22. It was Ciel who named most of the Resistance members, and she seems to love birds.
Fire, Ice, Lightning: Literally, as the simplified version of the Elemental Rock-Paper-Scissors compared to its predecessors, where, on the second game onwards, Bosses are always grouped in fours (one for each element and the fourth for a non-elemental). Three of the four Guardians, Fefnir, Leviathan and Harpuia, respectively, even embody these elements. Mega Man ZX would also follow this trend.
Evil Genius: Phantom note the only one of the five to try both a sneak attack and a boss fight before his stage even begins. His division in the Neo Arcadian army is also stated as the Intelligence Unit. He could also be considered the second Dragon as well, considering he's the most loyal to Copy X, to the point of trying to take Zero with him.
Sixth Ranger Traitors: Harpuia, Fefnir and Leviathan (they're stripped of their positions and later aid Zero in his battle against Omega.) The same is also true of Phantom by his verbal support, but he is stuck in Cyberspace.
Foreshadowing: Each game has at least one example before an important reveal, in the form of character's dialogues. In order:
Before the gauntlet that are the final levels:
Unknown Elf (the real X): "Go. Terminate that copy of me. Terminate with extreme prejudice..."
After one of the first missions:
X: "The Baby Elves will do anything to reunite with their mother. Stir the humans' minds and bring chaos... It's all to meet their mother, the Dark Elf... The Dark Elf that I sealed..."
Upon defeating Omega in the first encounter, Copy X and Dr. Weil issue a challenge to La Résistance to find out who can capture the Dark Elf first. Before leaving, Weil gives the following cryptic remark:
"Let's see how far you get with that body!"
Before being sent off to the Ragnarok core to stop the Colony Drop:
Four Is Death: Aside from the Four Guardians, there's the Elf Wars, that lasted for only four years, yet brought so much damage to the world. Partial subversion: The only reason the war ended on its fourth year was because of Zero only reappearing at that time. Also, there are four games in the series.
Four Philosophy Ensemble — the five major bosses in the first game: Copy-X (the Cynic), Phantom (the Apathetic and pragmatist), Harpuia (the Conflicted), Fefnir (the Optimist), and Leviathan (the Realist).
Four-Star Badass: The 4 Guardians technically qualify, as they're generals of their respective armies.
Among the Four Guardians: The loyalist, rule-keeping Phantom (choleric/melancholic), the reliable and civil Harpuia (phlegmatic/melancholic), the encouraging but Trigger Happy Fefnir (sanguine/choleric), and the self-centered but playful Leviathan (leukine/phlegmatic).
The last bit is a clincher, since Zero, who was created by the same Dr. Wily who started the entire Robot War in the first place, is the one who finally ended it. Of course he also stopped it by dying.
Zero 2 only slightly hints at the Forms system; after that, the players will have to rely on luck unlocking each of them unless they consult a guide. A player can possibly even go through the whole game without unlocking a single one (until completion, of course, where the Bragging Rights Reward for beating the game is the Proto Form.
In Zero 3, players tend to ignore entering Cyberspace so as not to lower their rank. However, entering the Cyberspace in a specific stage is key to obtaining the best foot chip in the game.
Guilt-Based Gaming: In this series, Zero can find powerups to upgrade his abilities and activate some temporary cheats. The problem about it is that the powerups are Ridiculously Cute Critters that you raise and "eat". The third game softens this by allowing you to equip some Cyber Elves without sacrificing them while the fourth has just one elf that mimics the abilities of the others.
Lampshaded in the first game:
Ciel: Have you ever heard of a thing called Cyber-elf? A Cyber-elf is an electronic entity that gives some kind of a power. But once they use their powers, they die... I feel sorry for them...
Halfway Plot Switch: Happens in Zero 2. The first half of the game has Zero taking care of missions for La Résistance, or, more specifically, for its new commander Elpizo, in preparation for his Operation Righeteous Strike. When the Operation turns out to be a disaster, Elpizo becomes the designated Big Bad of the game, and the second half is spent trying to find him, and stop him from his plans.
Handshake Refusal: Elpizo introduces himself to Zero as the new commander of the resistance and offers his hand after announcing his plans to destroy Neo Arcadia. Zero refuses both the plans and the handshake.
Hellevator: The Giant Elevator in Zero 3. You take a massive elevator deep into the earth to fight a boss who's based off Cerberus.
Honor Before Reason: The Guardians and the Neo Arcadian army are all heroic guys, but they are bound to obey the will of Neo Arcadia, even if that "will" is obviously either A. That of a fascist tyrant who goes against everything the city once stood for, or B. A human government who is greedy and uncaring.
Humans Are the Real Monsters: Revealed in one dialogue during Zero 3, stating that humans of the dystopian Neo Arcadia only indulge themselves in food and comfort, letting the authorities do the thinking for them while regarding the conflicts Zero and Ciel have been fighting as mere daily news on the televisions. The whole Government Conspiracy and Propaganda Machine aimed at the Resistance don't help. In Z4, Zero also further condemns humans fleeing from Weil's iron fist as cowardly beings who would do nothing about their refugee leader getting kidnapped just to avoid another war. It is not until Craft blows up the city that the humans finally wake up with terrible pain in their minds.
Dr. Weil also implies in the third game that Humans innately feel that ruling all the eye can see and making others work for them is the ultimate joy for them, and believes that no Reploid could ever understand this joy, although Zero counters this by stating that he doubts any decent human would understand Weil's viewpoint, either.
Humans Are Special: The villains all hold this view, to the extreme. But played straight in Zero 4, where Zero has a short line about how humans are the ones who can change the world and tells Craft the reason he failed is because he was a reploid built for war, while Zero was fighting for Ciel (a human).
Humongous Mecha: There is a Boss in the first game that qualifies, "Hittide Hottide". Needless to say that the entire mission is spent trying to destroy this monster. Also a borderline example of Battleship Raid.
Also, the Golems.
Hell the Giant and Carnage Force 0 from Zero 4, who are expies to the intro bosses from X2 and X3.
Idiosyncratic Difficulty Levels: Although it is only one uniquely-named mode, the Ultimate Mode present in all four games. It's almost always the hardest mode to unlock (all games present a Gotta Catch Them All requisite), with good reason: it's the best mode of play in the series. Simply put, it's a middle point for hardcore players who resent note The DS rerelease adds "Easy Scenario", which gives you all permanent cyber elf effects and the Ultimate Form where applicableNORMAL Mode, and casual ones and/or "newcomers" who resent Hard Mode, arguably enjoyable for both tiers.
Legacy Boss Battle: in 3, taking a secret detour in the second fortress stage will take you to a teleporter. Go inside, and you'll meet Phantom from the first game, or rather his "ghost" since he self-sacrificed. Defeat him and you'll get the Infinity Plus One Foot Chip.
Lethal Joke Item: Ever make "Junk" out of Item Crafting in Z4? They're actually ingredients for the Junk Armor, a set of armor that makes him even more of a Glass Cannon and doubles all damage he deals and receives. There are also S-crystals, which are never used as Custom Chips either, but make two of them and bring them to your friend Hirondelle for two free Sub-tanks.
Lethal Lava Land: Phoenix Magnion and Fefnir's stage in Zero 2; Blazin' Flizard's stage in 3.
Levels Take Flight: At one of the turning points of Zero 2 (right after the failed attack on Neo Arcadia and during Elpizo's subsequent Face-Heel Turn), Zero has to cross an entire air fleet of Neo Arcadian vessels in order to hijack and stop a missile that Neo Arcadia launched at the Resistance Base.
Living Battery: Cyber-elves, and in particular, the Nurse types, function this way.
Lost Forever: Zero 1 is bad about this with the Cyber Elves. In each stage, at least half of the enemy types in that stage must be killed roughly five times to produce a Cyber Elf. Failing to do so during the stage means you can't get that Elf later. What's worse is that the game will, about half the time, not even provide you with a sufficient amount on a straight run, meaning you have to run back and forth over the same area to trigger respawns of the enemy type. There's also the Underground Lab area, which has two Cyber Elves hidden in out-of-the-way places. If you beat the Data Recovery stage (where Maha Ganeshariff is the boss) without collecting the two elves, those two will be permanently sealed off. Finally, in the desert level, there is a Cyber Elf at the top of some collapsible platforms. The platforms not only collapse ridiculously fast, requiring precision timing to get across, but they never regenerate (as in, once collapsed, they never come back for the entire game), so you have to get it right the first time, restart your save to try again, or beat the game, reach those areas again, and give it another shot.
Zero 3 has a cross-platform example with the Battle Network chip Z-Saver [sic] in Ciel's computer. This is a once-only chance. Not once-per-game, mind you, once per cartridge. If it gets traded off, anyone else who gets their hands on the cart is stuck with whatever you traded the Saber for (which is sadly, most of the time, a Guard chip). There's always a Game Shark to fix that problem, though.
Multiple Life Bars: Bosses in these games have layered life bars. Zero can get them too, with a special Cyber-Elf.
A Nazi by Any Other Name: Neo Arcadia, after an energy crisis, had started persecuting Reploids as being Maverick for no real reason, resulting in a mass amount of retirement (IE, execution) of said Reploids, allowing for anti-Reploid policies that are heavily implied to include genocide, and the person who directly created these policies is himself a Reploid (and by that, it means an actual Reploid, as in not even something of X or Zero's caliber). It's kind of hard not to see the parallels between this and the creation of Nazi Germany, and more importantly the rise of Adolf Hitler.
Nintendo Hard: Especially the first two games. The critics even say that "it's not cheap to use cyber-elves to make the game(s) easier."
Specifically, in the first game, the bosses were very hard (to the point of putting in a skip system), you couldn't backtrack if you did use said skip system, you had to grind with your weapons to level them up, the cyber elves were very unforgiving in mistakes and gave huge penalties, took an absurd amount of energy crystals to fully level up, and weren't nearly as useful as the later ones. In Z2, the elves are more useful, didn't need so many crystals, there were two free e-tanks, you could get permanent power ups, and you could even learn special attacks from bosses; however, you still had to level up your weapons, and said special attacks were only available for A or S rankings. In Z3, you no longer had to level up weapons, it was easier to get upgrades, there were more opportunities to use elves, and there were useful armor chips. And Z4 was just so easy compared to the rest, it would take all day to compare it to the others.
Which is probably why the Compilation Re-release for the Nintendo DS comes with an "Easy Scenario", an option to play through all four games in one go with all the weapons, items, and cyber-elves collected and maxxed out.
No OSHA Compliance: In Z1, you have to restore power to your base so that the Red Shirts can take the elevator to the shuttle bay so they can evacuate the base. Because, apparently, there are no stairs, ramps, or ladders.
One-Winged Angel: Pretty much every single final boss, three out of the four members of the Guardians (Phantom has one in concept art, but is dead by the time the others use theirs in-story), all of the Eight Gentle Judges (though some of their transformations are only slightly bigger than their human forms), and, finally, a Pantheon. Boy, did Capcom go overboard with this one. The Guardians' transformations are referred to as Armed Phenomena; fanon has come up with similar terms for the other transformations.
Open Ended Boss Battle: if the player loses a life out on a mission, they may be given the option to "give up", where the mission is a failure but the story continues without the mission's rewards.
Operation Blank: In Zero 2, there's Elpizo's "Operation Righteous Strike", which is essentially an invasion of Neo Arcadia. It fails horribly, with many Red Shirts dead, and Zero having to rescue Elpizo before he's killed by the Guardians.
In the drama tracks. there's "Project Elpizo", an operation to create Omega, a Reploid that's a perfect ruler using the Mother Elf's program rewriting ability. TK-31 (Elpizo's former codename) accidentally found the data about this project, and because it's supposed to be a secret for Neo Arcadia, he's declared as Maverick by Harpuia. Eventually, he managed to run away from the country and changed his name into... you know... as well as starting his quest for power by stealing the Baby Elves.
There's also Operation Ragnarok in Zero 4, which aims for the destruction of Area Zero using Ragnarok.
Strangely, the fates of the three living Guardians after Omega's death are completely ignored until the Zero Complete Works, which says they died in Omega's explosive death throes. Z4 doesn't so much as mention them.
Power Trio: Ciel (Superego), Zero (Ego), and Elpizo (Id) in Z2.
Pre-Explosion Glow: All of the animal bosses glows before exploding after you defeat them. The humanoid bosses usually don't do that (except Phantom, Copy X (in the third game), Omega and Weil).
Previously On: Each game after Z2 features a prologue of sorts that narrates what happened in previous games (see Opening Scroll). The narrator in Z4 is actually a character introduced later in the same game: Neige.
Puffer Fish: One Mechaniloid in the fourth game is modeled after this. They exploded into spikes if left long enough.
Neige: I was amazed at how Craft fought to protect the humans. Hehe, it's kinda strange, a human falling for a Reploid.
Craft: Then I fell in love too.
Same goes for one Reploid, Andrew who actually married a human. He even went so far as to modify his age-appearance to match hers and stayed that way even after she died as a way to remember her.
Riding the Bomb: The latter half of a mission, including the level's Boss Battle, in Zero 3 takes place inside a missile as it was launched towards an unsuspecting target.
The Revolution Will Not Be Vilified: Zero is found by the Resistance to Neo Arcadia, an empire that Zero's friend X (hero of the previous series) created with the best of intentions, only for it to go bad after he left. The Resistance is full of spunky, heroic types with French names, and they're always in the right — with one major subversion. Elpizo, the leader in Zero 2, is zealous and aggressive; when his new methods fail, he goes nuts and becomes the game's Big Bad.
Robo Family: While the four never say it outright, some of the fandom call the Four Guardians "siblings", due to their similar origins and purpose. X can also be considered their "father" (and, by extension, Copy-X is their "stepfather". The four are loyal to both.)
Segmented Serpent: A variant in the second game: Hyleg Ourobockle's boss room has this as the battlefield itself, with Bottomless Pits below it. Said serpent can detach and its segments can form various shapes.
Sequence Breaking: In Zero 1, Leviathan will talk about your fights with Harpuia and Fefnir, whether or not you've even met them.
The Z-Saber igniting in the drama tracks makes the exact same sound as anotherLaser Blade. It makes the same sound in Mega Man X, at least in Japan.
Omega's second form has different-coloured arms and white middle body. You know, there's some other guy named Omega who has the same appearance... note I mean, Omegamon. You probably won't get the catch easily, because Omegamon's name overseas is Omnimon.
Heat Genblem, a turtle-based Reploid from Zero 4, uses a spinning attack that resembles Gamera's method of flight.
Dr. Weil's trying to crash Ragnarok into Area Zero heavily resembles Sonic Adventure 2's last story where the Space Colony Ark, after being given the seven chaos emeralds, ends up falling towards Earth's atmosphere due to a program that Gerald Robotnik made during his grief-enduced insanity and prior to his execution. Furthermore, one of the heroes ends up sacrificing himself in an attempt to stop the colony from falling into the Earth, complete with defeating the enemy fused to the falling colony. Coincidentally, both instigators of the event (directly or indirectly) share the same voice actor in Japan.
Another Street Fighter reference: the boss Maha Ganeshariff, who has what's obviously the Hundred Hand Slap of E. Honda.
A carry-over from the X series: the Japanese term is Repliroid; the English term is Reploid.
Zero 3 reveals that the animal-like Reploid bosses are known as Mythos Reploids, referring to the fact that they're all based on various mythological figures. The English translation slipped up and translated it "Mutos" (the katakana is myutosu, for those curious. Japanese transliteration of Greek can be sort of weird).
Stealth Pun: When you defeat an enemy with a bladed weapon, they split in half before exploding. In other words, they got Divided By Zero! Wakka wakka!
Also, the Ragnarok's core is named after Laevatein, a legendary sword (in the manual, anyway). Said core is sword-shaped.
The Stinger: At the end of Zero 2, Dr. Weil commands his creation Omega to act.
Talking Is a Free Action: Most bosses always take the opportunity to chat up the hero just before exploding. Even if they've just been visibly bisected down the middle.
Theme Naming: Bosses are named after various mythological creatures; Resistance members are named mostly after French names of birds. In the latter's case, the handle of the one who named them is French for "sky".
Time-Limit Boss: The very first Mutos Reploid that you fought in the first game, Aztec Falcon, had a time limit, specifically on the platform that will crush the hostages below. Another instance include the FinalFinal Boss, above.
Trial-and-Error Gameplay: If you're going for A or S rank, then expect to reload from your save file over and over while you memorize the layout of each level and the attack patterns of the boss therein. And god help you if the level doesn't end at the boss.
Tron Lines: Some stages have these in the background.
Turns Red: The enemies' attack patterns are modified once they're down to 1/2 or 1/4th of their hitpoints. Special mention goes to the guardians, who not only change patterns, but gain an attack that makes them invincible until they complete it. Moreover, they are covered in aura which makes it impossible to jump them without climbing a wall, which none of their areas have.
Two-Part Trilogy: At least before Zero 4 showed up. 2 and 3 are more directly linked, both dealing with the Dark Elf and the Elf Wars it played a part in.
Untrusting Community: The citizens of Area Zero in 4 don't think very highly of Zero and the Resistence at first.
Ungrateful Bastards: During the Battle for Area Zero, most of them didn't take too kindly to being rescued by Zero...
Unusual Ears: All of the Reploids in Mega Man Zero & cyborgs in Mega Man ZX seem to have these strange white headphone-like things instead of human ears, which is strange, considering that the first Mega Man had proper ears, despite being much less advanced.
The above is very much the norm in this continuity - even for the humans. The only characters in the entire Zero series who are shown to have normal, human ears are Neige (a human) and Dr. Weil (formerly human), making ''them'' the unusual ones.
Zero 3 actually distinguishes with certain fusion elves. Sub-tank elves? Won't hurt your rank if used outside of a mission. Life extension? Same. Double life? Same. Instant A-rank for one mission? You just lose one point, meaning you can still get from a B-average to an A-rank in the same mission you use it. It also offers the use of Satellite Elves, which don't die when used.
There's a bizarre variation in the second game: The Crystal Cave area is full of turquoise Red Shirt Reploid allies under enemy control; you're supposed to spare them before saving them, but if you kill them instead, you get a 1-up! However, killing them will reduce your mission points (which is important to your rank), and they won't become helpful NPCs at the Resistance Base like other Reploids you've saved.
Wake-Up Call Boss: Aztec Falcon, the first real boss in the first game, is known for shocking the players who have been used to the previous Mega Man games.
Weaponized Offspring: In 4, Popla Cocapetri (a chicken) can lay an egg with 2 legs that will run about, harrassing you. The egg is hard to kill, too.
What Measure Is a Mook?: Zero stops short of killing the Guardians when you first fight them, with no explanation offered. Granted, you find out later that they're Hero Antagonists, but their subordinates, who are similarly just doing their job, are all fair game for bisection.
The Guardians also apply this as What Measure is a Red Shirt. In the second game, Harpuia chooses to spare Zero when Zero is at his mercy, even though he spent the previous game retiring Resistance soldiers left and right. Later on, they also let Zero leave with Elpizo after slaughtering his entire army.
What Measure Is A Nonhuman: The main conflict in the series involves the dwindling rights of the Reploids, relentlessly persecuted for trivial reasons. Later, the humans receive this treatment as well, ironically from the most inhuman of them all.
White and Grey Morality: Deconstructed in the first two games. Barring the psychopaths (the bosses from Zero 3-4, Copy X, Elpizo, Omega, and Weil), no one in the war was truly a villain in the proper sense. This point is what makes the Guardians (especially encourager Fefnir and civil Harpuia) the most sympathetic antagonists in the franchise.
Even the never-matured Copy X and Maverick-intentioned Elpizo had their Alas, Poor Villain moments, and they both ultimately only wanted what was best for the people they were fighting for — just never learned what true sacrifice and heroism meant. Arguably, the only real villain in these games was Weil, who was behind the horrible events of the games' backstory, plus being involved in some way in the plot of the first two games which was before he was even introduced.
Surprisingly, Weil himself too. The Official Complete Works revealed that he started the whole Elf Wars because he thinks that Reploids, being just machines, were getting off too easy for the massive destruction caused in the Maverick Wars, especially once the plan to solve the Maverick problem was to basically install anti-virus software (the Cyber-Elves) and call things even. So he was more of a Well-Intentioned Extremist from the start; but, driven secretly to avenge only himself, he went through the Moral Event Horizon by creating the Elf Wars in the first place (and he went nuts even more during his exile). This shows how much this trope is deconstructed in this series.
Halfway through Zero 2, your missions are all the same: you who were helpful to Commander Elpizo must now intercept the runaway Elpizo. Guess what happens every time. Zero also failed to save X's body in time, as Elpizo destroys it, releasing the tightly-shackled Dark Elf in the process.
In Zero 3, you have to stop a missile from harming a residential area. When you arrive, the missile is launched, and then you ride onto it, trying to destroy the inactive Omega inside. Unfortunately, the Baby Elves hold you in the middle, long enough for the missile to reach its destination and claim thousands of lives. Ergo, Zero is prevented from saving any innocent lives other than Sage Harpuia.
Later, Zero tries to stop Copy X Mk. II, and then it's revealed that Weil is just using them as his Unwitting Pawns to become the ruler of Neo Arcadia.
In Zero 4, it's said that the Einherjar Eight Warriors are just distractions for the Operation Ragnarok.
Later, Craft pulls out a Heel-Face Turn (sort of) and tries to destroy Neo Arcadia and Weil using Ragnarok. You are sent to stop him, but right before the final boss door, the Ragnarok is successfully fired, claiming millions of lives. And then you fight him.
Zeroth Law Rebellion: Played with copious amounts of irony via Zero's final decision in dealing with Weil. The irony here is two fold: while Zero was not designed to be Three Laws Compliant yet he chooses to obey them of his free will, and in how Zero's actions are in perfect compliance with Law Zero. note The spirit of Law Zero is a threshold law with a very specific trigger (such as a mass murderer) for it to be appropriate.