These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Both Prometheus and Pandora, as they have energetic, dynamic boss fights with awesome theme music. It gets even better when you fight them both at the same time.
Broken Base: The nature of the existence of the Biometals is a point of contention with fans. Some feel that it's an excellent way to sort-of bring back the old characters without shoehorning them into the series, seeing it as having them "mentor" their biomatches. Others dislike the concept, as they feel it cheapens the deaths of these characters and/or they wonder why they couldn't just rebuild the characters themselves instead of putting their minds in chunks of metal.
Fans also see Vulturon as this. A headbanging robotic vulture skeleton who uses a guitar for a weapon. Not crazy enough? He can use said guitar to reanimated discarded metal, thereby creating zombie robots. And he does use that guitar for performances... usually to aforementioned zombie robots. His quirky rocker personality helps a lot.
Much like Charlie, Giro has amassed a sizable fanbase despite being dead.
The fandom has gradually taken quite the liking to Prometheus and Pandora. And if anything, when they were discovered to be Woobies, Destroyers of Worlds and then subsequently owned by Albert (in the span of five minutes or so, no less), their popularity among the fandom hit critical mass. For some, that was Albert's Moral Event Horizon.
Of the ZXA cast, Vulturon, for reasons explained above.
This seems to be what happened with the names of all the Biometal Users in ZXA. While Atlas, Helios/Aeolus, Siarnaq, Tethys/Thetis, Prometheus and Pandora were all supposed to be Saturnian moons, when you look at them in the context of Greek Mythology, they appear to be a random collection of Titans and other mythological figures with no other real meanings behind their names.
Also, the Sage Trinity has nothing to do with a Trinity, God, or Christianity. Apparently, they are named that just because there is three of them and it's just a translation choice anyway (their Japanese name translates to the connotation-free "Three Sages").
Siarnaq is actually the name of a giant from Inuit mythology.
Also noteworthy is the fact Homer often referred to Helios as Titan or Hyperion — both moons of Saturn.
Prometheus was the Titan who stole the secret of fire from the gods. The character in question here is self-explanatory in that regard.
Pandora's Box was a legendary artefact that reputedly brought mass ruin upon the land in which it was opened. Pandora here turns out to be suppressing her true persona and agenda. She is outwardly calm and emotionless, but reveals herself to have an insane, vengeful side when the player gives her that extra push.
Fridge Brilliance: Why do the Pseudoroids have extra eyes? It's likely a property of Model W, and considering it is very much a Eldritch Abomination thematically, and that Humans and Reploids are and consider each other the same now the logical conclusion on exactly how this would be seen as by the people inside the setting. Add in the dialogue the Pseudoroids have and you realize that at least some of them (like Purprill) were around at least in some form before gaining the power of whatever Model they were infused with; with their absolute devotion and belief to Model W you realize that they are mutilated cultists.
The tagline from this Japanese promotional trailer ("When fate must be stood up to... people shall Rock On") really explains the Screw Destiny theme of the series, and the Biometal's power to shape the Biomatch's destiny, as elaborated by Ciel.
The Enemy Mega Men and Albert's Co-Dragons' names are taken from the moons of Saturn. Saturn is known for its giant ring. Guess what shape Albert's collective Model W (Ouroboros) is?
Game Breaker: Model ZX's rolling slash, which can bypass Mercy Invincibility and deal continuous damage as Vent/Aile's still spinning. And after that, you can still follow up with your standard triple slash.
Model P's kunai spam is murder against enemies without Mercy Invincibility. Wipes out everything in seconds.
The downside, though, is that you'll get Lv 1 Victory, so you'd better do that in the boss rush. Unfortunately, it was later nerfed in ZXA, the attack instead generating two tornadoes that fly forward and only hit once.
Chronoforce's Time Bomb. Its only downside is that it uses a lot of weapon energy. It also loses all functionality in the final battle with Master Albert, who specifically whips out his own Time Bomb just to counter yours.
Goddamned Boss: Thetis makes sure to fight you underwater where he has such an edge it's almost unnatural, and he employs constant hit-and-run tactics while you're trying to keep your footing (on the three tiny ledges they give you) above a Bottomless Pit. Gate tried similar cheap tactics in X6, but Thetis perfects it. Have fun with all this on Hard Node and Boss Survival, by the way!
It doesn't stop there. Both games feature two gun-slinging protagonists — one male and one female, and at one point in the game, they have to fight the protagonist from a previous game.
Might be intentional on the creators' part: Advent featured an unlockable mini-game, Mega Man a, all in 8-bit, styled after the original series of games. A few months later, Mega Man 9 was released, in all its retraux glory.
Just Here for Godzilla: Arguably, but a good portion of ZX fans are Just Here for Biometals. More specifically, "Just Here for Playing as the Favorite Characters Who Come Back as Pieces of Metal that You Can Use to Change into Said Favorite Characters." note It makes sense, actually, especially for Model OX, which is based on Omega from Zero series. As a result, many fan arts for this series are about "Hey look! This is Model (insert your favorite character here)!" And the favorite character in question could be any character from the series (be it a major character or just a random boss) note are just a few examples, a character outside the series note theseare just a few examples, or even an original character.note thesearejust a few examples.
The latter set up a Gambit Roulette of his own to combat Albert and killed off his former ally by making it into a mission for the heroes. As much magnificence as Albert whipped out, Thomas may have actually outdone him.
What the player finds out during endgame is even worse. People are kidnapped by Slither Inc. during the uprisings and held captive. Serpent then preys on their fears to involuntarily transform them into Cyber Elves, which are then absorbed by Model W as sustenance.
Narm Charm: Activating a Biometal in the Japanese version prompts a cry from "R.O.C.K. On!" from your character. Woolsey'd to "Megamerge" in English.
The second game is also the best kind of Ben10 game that has both gameplay depth and character variety.
That One Attack: Some of the bosses have this. One example is Prometheus's skull flame attack where he summons skulls at the corners of the screen that fire at you simultaneously, requiring tricky maneuvering to avoid. Mitigated a bit by the fact that the skulls can be destroyed.
Serpent's (2nd form) flame attack can also be pretty rough. With him firing off four flaming rocks that stay on the ground while slow falling flames fill the entire screen and home in on you.
That One Boss: Flammole if you're going for a Level 4 victory. Why? His weakpoints are his arms. His arms make up the majority of his sprite. We're talking like 75% of it. In addition, the only time his arms aren't vulnerable is when he's stationary (from the front). The problem? He's only stationary for a brief moment in between his attacks, meaning hitting him without damaging his arms requires quick action and very precise timing.
Fistleo if you want a Level 4 victory. His weak point is his freaking head. A majority of your attacks will hit his head and he has some hard-to-dodge attacks. On top of that: the bastard can heal, and he does it frequently. So you have to constantly be on the attack to keep his health down. If you're going for a Level 4 victory, this means you have little time to make sure his weak point is out of your attack range before striking. Bonus pain if you're playing on Hard.
Fistleo is pathetically easy compared to Flammole because, amusingly enough, Model HX's triple combo doesn't hit his head if you use it with your back facing him, and in Overdrive the triple combo hits For Massive Damage.
See here. You may want to have clean pants standing by.
Strangely, it seems both fire-themed bosses from the first game ended up as That One Boss solely for Level 4 victory attempts.
The Ouroboros stage. There are blocks that can be destroyed and then regenerating. If you're standing on the block's space when it fully regenerates, you die. There's also spiked regenerating blocks and Bottomless Pits right under them. Oh, and this part (Ouroboros-3) is right after the Boss Rush and right before the Final Boss room. Have fun.
That One Sidequest: The Area K subtank. The fact that you can't get it on Hard Mode counts as mercy.
The Area X Sub Tank as well. It's much easier than Area K's, but it involves nearly 40 minutes of running back and forth to Area L, going through (at least part of) the stage 12 freaking times, to pick up items for NPCs. There is even a bit of Guide Dang It to boot, since you are not told just where these items are or that your reward will change if you keep doing it enough times.
Tier-Induced Scrappy: ZXA's Rospark form, of the low tier variety, since it moves very, very slow and its only useful gimmick is climbing ropes.
Viewer Gender Confusion: Struck everyone who was paying attention to Advent previews with respect to Atlas and Tethys (see Tomboyish Name for one of the reasons). The first images of the enemy Mega Men showed them in armored form, so fans had no clue that Atlas was a "she" and Thetis was a "he." It did not help that their Japanese names (Atlas remained unchanged, while Thetis was Tethys) were that of a Titan and Titaness, respectively. Likewise, their Biometals were a man and a woman. Thankfully, this was rectified by gameplay videos and subsequent artwork, but the Fan Nicknames of "Reverse Trap" and "Trap" would stick.
Woolseyism: "Live Metal" to "Biometal"; "Falseroid" to "Pseudoroid"; the aforementioned Fun Acronyms and Charming Narm; "Girouette" gains the nickname "Giro"; "Helios" to the much-more-sensible-for-an-air-elemental "Aeolus"; "Serpent Company" to "Slither Inc."; a few boss names as well (although one simply goes from "Condorrock the Vulturoid" to "Vulturon the Condoroid"...).