Where Anetta's Well-Intentioned Extremist eco-enthusiasm ends and where Wily's (and PlantMan's) brainwashing begins is... unclear. Also, is PlantMan loyal first to Anetta or to Wily? In Battle Chip Challenge, he remains with her after Anetta has abandoned the WWW.
Is Raika a jerk who only cares about orders, or a soldier who honestly cares about his companions?
Is Chaud an elitist jerk who is ruthless in his orders? Or is he just putting up the act to appear tough in front of his father?
Anti-Climax Boss: The Life Virus at the end of the first game. Despite getting hyped at as Wily's ultimate weapon, it proves a pushover (first game bosses are the easiest in the series), with a predictable set of attacks and its health is low enough that it's possible to kill it in a single turn, even with the temporarily beefed-up MegaBuster.
Awesome Music: The music in general stays fairly high-quality throughout the series. Some examples of particularly awesome music, however:
In Network Transmission when the Professor reveals himself after Zero's defeat, the whole Cyberworld MegaMan, ProtoMan and Zero are standing in inexplicably starts shaking. This shaking is never mentioned again.
Battle Network 4 is filled with these. Although you could blame how the scenario system works as to why nobody ever seems to comment on most of the stuff, it doesn't change the fact that there was some seriously weird stuff going on. Explanation This is because, to save on programming, characters ignore events unless they are directly affected (i.e. it occurs in their immediate location).
If you look at the series as the continuous story it is supposed to be, the entirety of Battle Network 4 is a massive BLAM. The game ends with a meteor about to destroy the planet, and it's resolved by everyone on the planet cheering for Lan and MegaMan. In BN5, none of this is ever mentioned, although Team Colonel offers a small nod to its predecessor, with the trophies from the three tournaments that took place are on top of Lan's bookshelves.
FreezeMan from the same game. The fact that he's an Aqua Navi standing on ice panels causes him to take quadruple damage from any electric attacks, so two ToadMan or ThunderMan chips should be enough to take him down. What's more, since electric attacks causes enemies to be paralyzed rather than flinch, you can immediately hit him again.
PlantMan in 3 is a pushover due to the overabundance of Fire chips in his dungeon, has a predictable set of attacks and movement as well as lacking any kind of shielding mechanic the likes of BubbleMan, FlameMan and DrillMan are infamous for.
The fanbase is decidedly split between those who think the second and third games are crown jewels, and those who think of the sixth game as such. 3 is beloved due to its storytelling and having the most extensive gameplay in the series, but also criticized for its massive amounts of hidden information that can only be found in out-of-print materials. 6 is well-regarded for removing 4 and 5's Scrappy Mechanics and improved some other features (compare Cross System to Double Soul for example) but some of the enemy bosses are regarded as uninteresting and the English version gets a lot of detractors for removing every singleBoktai content as well as the chips related to the Cybeasts.
Then there's the infamous debate about whether version-exclusive contents are totally fair or blatantly favors one game but not the other, the most notable example being the Souls and Crosses in the second half of the series. Though this gets less flak nowadays with some wanting to mess around with their preferred options in battle.
The inclusion of EX viruses in 4 and 5. Some fans might enjoy the extra challenge, others are annoyed by how they end up in an "extra effort same wage" situation. (EX viruses have higher hitpoints and damage output from their vanilla counterparts but gives out the same chip) V2 and V3 viruses (and their chips) are off-limits until post-game, which makes the players somewhat underpowered, especially in 4. Their palettes are kind of ugly too.
The graphics overhaul for the second half of the series divided the fans over which art style is better. Although this is mainly caused by BN4's overall poor reception and the graphics actually slightly improved in 5 and 6.
Crack Pairing: Serenade and Slur. Genderdebates aside, these two are often paired together despite never met at all (Serenade in the manga and BN3, Slur in the anime). Although this is probably because both of them are elite-tier and feminine Navis so they are often shipped together like rivals. Some fans even slipped Bass into the pairing and make those two fighting for his affection as well, even though Bass was the one who killed Slur.
Poor, poor Mayl is the target of the Het Is Ew part of the fandom usually called the "Pink Fiend" by the yaoi shippers. In fact, even on the hetero pairings she gets some heat for hogging and having a monopoly on Lan (some say at least the Yaoi has variety), partly because of the lack of female characters around his age in the games. This results in Lan being paired with other girls who he barely had any serious contact with in the series by people who are tired of the Lan/Mayl pairing. Some other alternatives are Sal/Lan, Jasmine/Lan, Princess Pride/Lan, and even some Anetta/Lan. The latter three call upon the anime mythos, since that's where Jasmine, Mayl and their respective Navis are love rivals, where Pride/Lan pairing originates and also where Anetta isn't crazy.
The reverse also applies with Jasmine around Mayl/Lan shippers.
As a rule don't mention Chaud/Mayl around the above pairing.
For the yaoi side, Chaud/Lan vs Raika/Lan vs Chaud/Raika, and lets not forget about the Navi/Operator pairings (Lan/Bass, Lan/Protoman). This get even more complex with the dark Navis, for example, Dark Megaman/Lan or Megaman/Lan.
There's a very good reason Mr. Match has been in five out of six games. HeatMan also makes an appreciated return in Battle Network 6.
Higsby HAS appeared more often than the majority of the supporting cast.
Princess Pride (in no small part to her Adaptational Heroism self from NT Warrior). Her personality change in the fifth game helps too.
Bass. Holy freakin' crap Bass. He might very well be the most popular Navi in the entire series.
Punk.exe isn't especially popular among the fanbase (having almost no characterization), but his existence is an expression of Keiji Inafune's love of the classic Mega Man Killer (who actually was a darkhorse from the original series).
Most of the teammates of Team Colonel and TeamProtoMan in 5 are very popular since they are some of the most useful allies Lan and MegaMan ever had in the series, even when some of them only appear in that particular game.
Fanon: There are several individual canons in three sets of media for the series: the games, the anime, and at least two manga series (though only one was published in America). Some fans mix details from all three, such as Mega Man being Lan's brother in the anime or manga timelines when neither adaptation officially adopts that plot point.
In the anime, Roll has an increasingly blatant crush on Mega, who is Oblivious to Love (much like his operator). Some fans believe that MegaMan knows of Roll's crush. Some of their stories portray him as being so lovestruck that he is willing to do anything for her sometimes at the cost of Lan. She's also depicted using the evil chip from the anime on herself intentionally and shamelessly flirt with the other Navis to make MegaMan jealous for not responding to her affections. This occasionally overlaps with Roll joining a villainous group, presumably because her expyHarp Note did the same thing in Star Force 2, albeit for different reasons.
There are also plenty of fanfics that portray Mayl as desperately wanting any form of love from Lan to the point of tricking him into giving her affection or leaving him for another man; the disturbing part is that they are still 10 in some of these stories.
Many fanfics love to portray Mayl as being overtly possessive of Lan to the point of her getting upset at him even interacting with other females.
Also the infamous link between Lan and MegaMan. In canon the details are quite vague, outside "if one dies, they both die". In some fan works it can work as anything from telepathic communication to feeling each other's senses to even merging their bodies.
Also in some fan works using the Japanese names there is the issue of attaching honorifics to an operator's name. Some people treat it as a personal pet name, such as Rockman calling Netto Netto-kun and getting jealous if any other navi used "-kun" when referring to him. Honorifics are simply a form of respect in Japanese and are used when talking to other people.
Many people like to portray Dr. Hikari and MegaMan as always holding secrets from Lan, usually under the context that he isn't ready. While in canon there is no indication of a lack of trust towards Lan.
Fan-Preferred Couple: Tying into Fanon above, NT Warrior informs a lot of Battle Network shipping (like, say, Chaud/Yai). But since that's NT Warrior material, the details are on that YMMV page.
Fanon Discontinuity: Some people cut off the entire second half of the series in their minds, though most people only behave as though the fourth game never happened (the fifth game certainly behaves as though Red Sun never happened, as Lan and Raika treat each other as new faces).
Also there are plenty of MegaMan-becomes-human-again stories where once he comes alive, Lan is completely forgotten and replaced with Hub.
True love stories where Mega Man and Roll try to set up Lan and Mayl together.
On the other side there are plenty of Mayl/Chaud stories where Mayl is tired of waiting for Lan to notice her and all she wants is a relationship. This also usually happens with crossover characters as well.
Betrayal fics where the government decides Lan and MegaMan are to powerful and try to separate them, imprison them, or delete MegaMan. That this was the basis of an arc in the Mega Man NT Warrior manga helps.
There are plenty of alternatives where MegaMan tells Lan that he is his brother.
AU stories where Hub is still alive.
Or if Lan died and Hub was still alive.
There are a few divorce stories that feature Lan's parents splitting up and Lan trying to cope with it.
Some stories will have KnightMan a girl underneath the armor for Lan/Pride fics. (WoodMan has been declared female in at least one fanfic, though not tied in to any Lan x Sal shipping).
Bass and Serenade shipping fics aren't unheard of, most of which treat Serenade as a female.
Faux Symbolism: Serenade is supposed to be a perfect being, incorporating aspects of both genders (hence the androgynous appearance), and has attacks named like "Saint's Light".
Bass, by comparison, is darkness-based like you wouldn't believe. Wants to kill humanity, wields Dark Power from the instant of its discovery, etc.
"Funny Aneurysm" Moment: In the early 2000s, the idea of cyber crime wreaking havoc on a global scale seemed pretty far fetched. Then came wave after wave of hackers breaking into company databases to steal money, identity information, and expose top-secret and scandalous information and suddenly Battle Network's antagonists doesn't as unbelievable as before.
Goddamned Bats: Viruses in the later areas of the game (especially the more maze-like ones) will constantly distract you from any task you happen to currently engaged in (e.g. running from the monsters in Netopia Castle network) and will take up far more of your time than they deserve to. The viruses in the later portions of the Undernet and any post-game Bonus Dungeon are so nasty they ascend right to Demonic Spiders.
Hard Heads are almost constantly shielded viruses that un-shield only temporarily to launch a cannonball that will punch a hole in your field. At higher levels, they can box you in if you aren't careful.
Mole viruses in the third game have low HP, but they are immune to everything except from ground-affecting attacks. When they emerge to attack, they always appear behind you, giving you a short window to circle around and attack them.
The Lark series of viruses - those that drop the Wide Shot chips - fire shots that cover a wide area in battle. Mercifully, they never attack when they're in the middle row, else their attack is undodgeable. Not so mercifully, the wide coverage of these attacks make them notorious for breaking in-battle Mystery Data, sometimes within the very first second of the fight.
Appley viruses in the 5th game pretty much serve to ruin a player's attempt at S-ranks or 1-turn Liberations. Most of the time they reside in their shell, only being vulnerable when emerging to attack. The shell makes them immune to everything but Fire attacks. Not even Breaking attacks work on them.
Goddamned Boss: We had too many examples, so they got moved to the trope page. In summary:
Many of the bosses from Battle Network 2 have gimmicky and obnoxious attack patterns that are less interested in being challenging and more interested in being completely unfair, usually through some combination of Spam Attack, Super Speed and being only vulnerable when they're about to attack* which they rarely do, making it frustrating if you want to obtain their V2/V3 chips by beating them under a strict time limit.
BN3's BubbleMan hides behind a huge rock and a hole in the field designed to Spam Attack for him, making it hard to get an opening.
BN4's ShadeMan, who always has some trick to keep from taking damage.
Good Bad Bugs: This is actually a gameplay mechanic. The introduction of the Navi Customizer in the third game allowed players to customize MegaMan to endow him with various abilities, but if you broke any of the rules of customization, MegaMan would glitch, possibly damaging himself or even the network. Some of the bugs are unambiguously negative (misplacing an HP+ program will cause Mega to lose health in battle), but some of them have unintended combat applications that players exploit anyway.
Bugging the Humour program in the latter half of the series causes MegaMan's "mood" to change at random, allowing the player to semi-reliably deal x2 damage because it was on full sync or anger for a few seconds. Also useful is the bug that causes the charged shot to create Rock Cubes, which can be airshot or punched into enemies for 200 damage.
Battle Network 3's Bug Style is entirely about this: you unlock it by deliberately glitching Mega before sending him into battle, it endows you with a positive and a negative bug at the start of each fight, and as you level it up, it gives you the Bug Stop program (which ignores Navi Customizer bugs so you can have a little more freedom when you customize Mega) and the Dark License program (which allows you to use certain Giga Chips without opening a Dark Hole in the field first).
An actual coding mess-up happens in the ProtoMan tournament fight at Blue Moon. His AI insists on doing almost nothing but spamming Fighter Sword, but only from the center-right row. An Area Grab makes him entirely useless in combat.
Good Bad Translation: For some reason, the three-Spreader Program Advance in Network Transmission was translated into English as "GigaDeth", which Roahm Mythril noted just begs to be said with a heavy metal growl.
Growing the Beard: It did so steadily between the first and second game and the second and third, the latter of which is widely regarded as the best game in the Battle Network series for its solid plot, stronger characterization, Tear Jerker moments, and battle improvements. The series was then hit with the inverse of this trope in the fourth game, which was hastily put together in an attempt to cash in on the popularity of the third game. While the series regrew it in 5 and 6, the shock from the mediocrity of the previous game led to the franchise's fall from public icon to cult classic.
Harsher in Hindsight: A scene in 3 where Mamoru nearly dies from complications during a WWW malware attack on the hospital around the time he was scheduled for an operation becomes more sinister when you realize that it is theoretically possible to break into a hospital's intranet and tamper with the vital equipment hooked into its network via their embedded systems.
In 3, all BBS posts made by Undernetters are anonymous.
The Undernet in general is portrayed as a Wretched Hive. In the 00s, this became what the Dark Web was portrayed as, and in 2015, what the Deep Web and Dark Net were portrayed as albeit Nightmare Fuel heavy.
Bridging this and Harsher in Hindsight, over the course of the early 200x years, malware attacks have increased in frequency and become more high-profile. Between Flame, Stuxnet, and the spam attacks made against Spamhaus that threatened to knock out an entire major router node, it's clear that the Battle Network series is eeriely prophetic about cyber warfare.
In Battle Network 6, one of the sidequests involves finding a lawyer to deal with the quest-giver's fraud case. The lawyer NPC you talk to turns out to be a boisterous, hotheaded crusader of justice that loves to shout "JUSTICE WINS!". This game was released a year before Mega Man Powered Up introduced us to its incarnation of Fireman.
It's the Same, so It Sucks: Go ahead. Say you're glad they're keeping the old graphics and Internet in the BN1 remake around fans. Although this is because the original Internet was very ugly looking and difficult to navigate, which may be mitigated by the map function revealed in the preview.
Lawful Stupid: Duo.EXE may fit this alignment in this series, seeing how he wants to destroy the whole planet for not fitting his standards of morality. Some of Duo’s dialogue even suggest that he destroys any plane, with even the smallest hint of malice, but thankfully it's a bit ambiguous. He definitely fits the Lawful Stupid alignment in the Anime all the way through, possibly even falling into Lawful Evil, as the first planet he destroyed, washisown. This seems especially ruthless from him, as nothing showed that his creators as really malevolent in any way. Even worse, he was originally just a program designed to distribute cybernetic technology, and internet through space, so him being a self-appointed judge of whole worlds, makes Duo seem like a maniac with a God complex, most probably being responsible for much more death and destruction than any of the species he judged guilty and exterminated.
Duo's Anger Impact has become the symbol for how much everyone hates Battle Network 4.
Mis-blamed: A Let's Play of MMBN1 criticized some players for not knowing what is a Program Advance (P.A.) because they didn't talk to NPCs who mention it all the time. The problem is that it's not that they didn't know about what it is, they actually didn't knowwhichBattle Chip combinations form what kind of P.A. at the first place.note There are some exceptions, but those only apply to really basic P.A.s. Making things even more confusing is that some P.A.s might get carried over to the next game but require different chips such as PoisonPharaoh, 2XHero and MasterStyle. It's like the Harvest Moon recipes, except that you cannot do things like bribing NPCs with gifts if you want them.
Narm: Duo's Anger Impact move, which has him projecting a giant pink angry face as a laser beam of some sorts. It looks silly, especially in contrast to his default super-stoic expression.
This also happens with some of the scenarios. The fact that Mayl and Ms. Mari are so excited for an internet-controlled dishwasher of all things after all the hijackings of household appliances can be somewhat silly.
Ms. Madd herself from the first game seems like she was built up for this. However, her expression coupled with her actions and taunting of Lan make her surprisingly threatening. Her Navi, on the other hand, is just plain ridiculous.  called attention to how awkward it looked when he was bouncing up and down while Roll was on her back.
In Megaman Battle Network 3, at one point you must fight a custom Navi as a boss to advance in the ranks. This actually changes depending on your version. In White, you get Mist Man who has a rather unique appearance. Blue, on the other hand features BOWL MAN◊, who throws bowling balls and bowling pins at you. It is simultaneously unintentionally hilarious, yet charming and awesome at the same time. Especially since they are ranked Undernet navis, and they are both decent people.
Drillman.EXE from the same game. His design and Dumb Muscle attitude is unintentionally hilarious, yet his status as That One Boss forces players to adjust their folder and their playstyle.
The Waterworks. You go through the stage and then defeat a Mini-Boss. Okay that seems all good...until you realize that now the water is actually poison so you have to go all the way back to the Government Complex' and all the way through the stage AGAIN to fix it. This is probably the worst offender of Battle Network'' padding.
The Castle stage in the second game could also be bad, but a lot of it can be avoidable if you just run out of the way of the zombies.
The Hospital Stage in the third game also comes dangerously close, since you have to use up fire chips to progress. Thankfully you can easily get fire chips in the area so that the game doesn't become unwinnable, but you have to run around and hope you attract enough fire viruses to drop one. However, if you have enough Totem chips lying around you won't have to do this, and they're actually quite easy to obtain even before the hospital stage and very practical. Same with cheap-damage dealing fire chips.
The Internet Fire is even worse. You have to spend Aqua chips to douse the giant bonfires all over the cyber-world, but this time, the virus encounters don't change - you'll have to detour to certain places like Yoka area if you need to restock your aqua chip supply.
The BubbleMan scenario is definitely this, which may be one reason why he's hated. You have to chase him all the way from Mayl's homepage to the Yoka area, leave and chase down his underlings for the Needle (three times), return to Yoka area again, leave and obtain the Press program, return to Yoka area once more and then wander through the gratuitously large compressed path maze to find BubbleMan's dead end. Shoot the bastard dead.
The Liberation Missions in 5. At first, they seem pretty easy and still puzzling to do as the games go on, and even offer a "prize" if you complete them at a target number or even before said target number. This would be all good if it isn't that the target number becomes lower and lover to the point where you just need to do trial and error to do so, especially when the Nebula/Undernet missions have known Mega/Giga chip that are required to open said areas.
Player Punch: The FlameMan story arc in 3. Not only Lan fell into a Heroic B.S.O.D. after being tricked by Mr. Match to burn SciLab, almost killing his father in the process but Lan and Mega's reactions to Mr. Match giving the shady data showed that this could have been avoided at the first place, but the plot cannot progress unless you did what Match wanted you to do. And this is right after Lan is honored as a hero for saving the Beach Hospital from Anetta and PlantMan in the previous arc.
Play the Game, Skip the Story: The games adhere to bizarre "Capcom Science" and follow a strict plot formula making it really predictablenote Starts with minor terrorism acts, Lan and MegaMan stopped the villains but they got what they wanted, rinse and repeat (insert misfortune for Lan somewhere in the middle of the story) until the final dungeon, Hub Ex Machina., but the games are actually more notable for the complex and unique gameplay. The fourth game is an exception though due to introducing a slew of Scrappy Mechanics and the plot is ridiculous even by Battle Network standards to be overlooked.
Rescued from the Scrappy Heap: Dark Chips are hated in 4 due to their impracticality, but in 5 they can be used for Chaos Unisons, which gives Megaman a powerful charge shot based from the Dark Chip used for the Chaos Unison without any drawbacks as long as the charge shot is released with a proper timing, which is easy to do anyways.
BubbleMan.EXE, the boss and cause of one of the most obnoxious segments of Battle Network 3. He also loses major points for being integrating Dirty Coward tactics into his boss fight; he has a hole in his field to interrupt your advance, is constantly deploying obstacles that you have to get around, deploys a shield when his health gets low, and his V3 ghost rematch won't fight MegaMan without the hero being at no more than 25% of his Max HP.
CloudMan and CircusMan are as hated as BubbleMan is. They are obnoxious in bossfights and cutscenes while getting away with what they usually did due to their ridiculously strong Plot Armor. The latter gets "bonus" points for being a creepy Monster Clown.
Chisao, Dex's little brother, does little but cause problems for other people. In his very first scene, he basically hijacks the subway system by preventing anyone from getting on until they find his big brother for him. While getting kidnapped during the Zoo Incident wasn't technically his fault, it didn't really do much for him, either. In Dex's storyline from Battle Chip Challenge, he tries to convince Dex that he should replace GutsMan, and in Red Sun, he actively tries to sabotage Lan's ability to compete in a local tournament.
Some fans aren't at all fond of Mayl, Dex, Yai, and their Navis on the grounds that they rarely do anything besides send Lan or Mega on errands and get into trouble. It doesn't help that their competence regressed with each installment and their passiveness in 6 allowed WWW to kidnap MegaMan and turned him against Lan.
Glyde isn't particularly hated, but he has so little effect on the plot that he's actually considered to be the most worthless character in the games due to being The Unfought and not having a unique moveset, things that GutsMan and Roll do not suffer from. He has maybe one or two scenes of Cutscene Power to the Max in the first two games.
Any point where you need a certain chip of a certain code to progress the plot. Especially if it's acquired from a rare encounter virus. Battle Network 3 players will be reminded of "Iceball M". Battle Network 4 players will recall the entire ColdMan scenario.
The Press program which allows MegaMan to walk on the tiny paths. The problem is that while on the tiny paths, Mega Man moves much slower and random encounter viruses still show up, which may cause you to forget which direction you were moving in.
There was also the Energy Change program which is required during the PlantMan and FlameMan scenarios where you have to either use a heat (PlantMan) or aqua (FlameMan) element battle chip so you can burn a plant/extinguish a fire which permanently gets rid of your battle chip. The Flame Man scenario gets bonus points since you have to extinguish every single fire and it takes place across several different areas on the internet as opposed to Plant Man's scenario where you only had to burn the plants that were in your way and were only confined to the Hospital's computer network. Since switches and portals and free bonus chips were located under specific plants, you could also Save-Scum to conserve your Fire chips. The hospital also had a few viruses you could earn Fire chips from to replenish your stock. The FlameMan scenario offers you neither consideration.
While Style Changes are not hated, the element is determined by the number of viruses of each element that have been fought, which is incredibly annoying to keep track of, considering how the main game requires you to run through multiple environments while still leveling up the same Style Change. Elec Styles, which have very little raw power, get hated the most. The nerfs to the Megabuster since the third game plays a huge factor, since Elec Style is supposed to be the speedy style with an emphasis on continuously stun-locking enemies-which is possible with power-ups but not with the more-limiting Customizer.
3 forces players to keep only one Style Change as opposed to 2 in the previous game, making it harder to adapt to various bosses and harmful environments in the late-game dungeons. It also doesn't help that various rare chips can only be obtained with certain Styles, so giving up the Custom or Team Style can halt one's progress towards completing their Library (barring getting really lucky with Chip or Bugfrag Traders) until they earn it again.
Also in 4, Dark Chips embodies all kinds of impracticality. Overpowered chips that appear when Mega Man is "Worried", but upon use, not only do you permanently lose 1 maximum HP after the battle, you're restricted from using SP Navi Chips. Especially bad since you still couldn't use "dark-type" chips, DS Navi Chips, or Evil Chips like Muramasa or Anubis until you're fully tainted from a lot of Dark Chips. Gets better in 5 where you can use them for the new mechanic Chaos Unison.
Regarding Navi fights, BubbleMan and DarkMan's beta forms will only show up if MegaMan's health is low and if there is a bug in the Navicust respectively.
A minor one, but in 3, Dex moves to Netopia late game. As such, you can't jack into his computer or use his shortcut to ACDC Square for some time.
Similarly, you cannot buy Battle Chips in Aster Land during 6's endgame since Tab joins Lan and co. to the final dungeon.
Forced tutorials at the beginning of every game. Even if you know everything about the Battle Network series, each game will put you through 3 tutorials usually on things you already knew like only using chips that are the same or those that share a code.
Seinfeld Is Unfunny: Just try viewing videos on YouTube of the fifth and six Mega Man Battle Network games; then try viewing ones of the first. The first game appears so laggy and bare-bones. (No style changes, no Navi merges...) It's pretty obvious that they were still experimenting. Not to mention, with the amount of Fake Longevity it was hard to get into the first Battle Network game because of all the tedious backtracking, hideous and convoluted main internet and artificially-lengthened stages.
Sequelitis: The second half of the series, especially the fourth game. The third game rather coherently ended the Dr. Wily plotline, the Bass plotline, and ended with MegaMan's Heroic Sacrifice. Following that the series had a major graphical shift, Style Changes were replaced with Soul Unisons (among numerous other gameplay changes), and Dr. Wily and Bass are somehow still alive. The plots also got quite weird, with the fifth game arguably taking the cake—the Big Bad's plan is to link the literal souls of everyone on earth via the Internet.
Story-Breaker Power: You can play with a fraction of that power with Hub Style in 2, the Navicust Program Hub.BAT in 3-5, and the Gigachip Hub Patch in 6. All but the last cut his max HP in half but grant almost every non-HP-increase passive ability at max power.
Compare Battle Network 1 with the later games, especially 2 and 3, before Capcom Sequel Stagnation set in. It's fairly clear they were still getting the hang of things.
The sixth game to the fourth and fifth.
And for that matter, the fifth to the fourth. It has an actually developed plot.
That One Boss: There's at least one per game. A more thorough list is detailed here, but here's a brief list:
ProtoMan.EXE is usually one of the most aggravating bosses to fight in most games, if only because he tends to block anything thrown at him with his shield until he comes out to attack, which he does very quickly, leaving only a small window of opportunity to strike back.
DrillMan.EXE in 3, for being nearly impossible to hit without breaking chips, which were either scarce or impractical in the first three games.
BubbleMan.EXE in 3. The continuous spew of damaging bubbles not only blocks your attacks, but also severely hampers your movement and a new one is made the instant you blow one up. Coupled with all the other obstacles thrown on the field and the fact his third version can only be encountered when Mega's at critical health...
QuickMan.EXE in 2. His attack pattern is very similar to Proto Man's above. The only saving grace is that it has limited variety in attacks and has low hitpoints, which stems from QuickMan being an early-game boss.
Bass, being a Bonus Boss, is normally exempt from this trope, but BassXX in Double Team DS is considered ridiculously unfair even by Bonus Boss standards, some going so far as to call him a full-blown SNK Boss. He has so much HP it's actually possible to run through your entire chip folder before defeating him!
SkullMan in Battle Chip Challenge has a great deal of health, a powerful attack, and has a scarily well-built program deck. His power chip is the Curse Shield, which not only shields him, but has an absurd amount of HP in its own right and it will eat your attacks for breakfast (and every time you hit it, it'll take a bite out of you, too). To add some nasty icing to this awful cake, SkullMan is often found on a poison stage, which will eat through your health and chips while you struggle to land each attack, hit by individual hit.
GridMan in Battle Network 5. His support clones will regularly block your shots, charge to attack you, and make it very difficult to efficiently Area Grab him since even when inactive and dead they take up panels along his front row. GridMan himself meanwhile has a lot of HP (2000 in his strongest form), is immune to flinching, tends to stay in the back row out of range of many attacks (again, Area Grab is tricky to get off properly), and his attacks, particularly when used alongside his clones, aren't easily dodged.
It's not particularly hard, to be honest, but you'd have to search hard to find five or more people who enjoyed the carnival levels in BN4. Brrr... that music.
Actually, what about the waterworks level in the first BN? You have a (somewhat) long stage full of slippery ice. It seems like you deleted what was causing the water to get held up but guess what? Now the water is purple and everyone's poisoned so you have to go through the stage all over again.
For that matter, the Power Plant, also in the first game. While veterans to the series won't mind the lack of post-battle healing (the later games had it as a facet of the system as opposed to a one-time gimmick) there's the fact that you're on a limited battery life, have to solve frustratingly vague logic puzzlesthe random battle rate is through the roof and a large part of the level is an invisible maze. Oh, and did we mention that the stage ends with three-round back-to-back-boss fights, with one of them being a Hopeless Boss Fight and the other pits you against ProtoMan?
The third quarter of BN 5 makes you navigate the labyrinth that is End Area, which is harder to navigate than the Undernet, has 5 areas and two Liberation Missions compared to Undernet's 4 and one Liberation Mission. Due to this said portion of the game is spent on lots and lots of backtracking around End Area...let's say after passing that part of the game you will be sick of it.
In the original game's school network, you have to input passcodes to open gates and the answers are given to you (i.e. count the number of chairs in the classroom, that number is the passcode), however, some gates don't give you any clues meaning you have to guess and if you're wrong too many times, the passcode changes. Thankfully, it does tell you whether you're too high or low and if one digit is correct, you're told which digit to change.
In 2, the Freeze Man scenario requires a lot of backtracking between Netopia and the Undernet.
In 3, the World Three guard robots have security claws that will take you to a certain checkpoint if you get caught. While the claws do have patterns, it can be difficult memorizing them and there are times when a security claw overlaps the shadow of another security claw making it easy to get yourself caught. Some are also ridiculously fast giving you only a few seconds (or less) to run past them while others are incredibly slow forcing you to wait until they pass you.
MetalMan's scenario in Blue Moon. It involves Tamako forcing you to study from her master (a Navi by the way) before you can challenge her. Said master then drags you to a fetch quest for food AND drinks in the Park Area. Some might make a mistake of only bringing him the drink, since he only mentions getting him food when you talk to him the second time. Only then will he teach you the minigame portion of the scenario, which involves punching rocks with very precise timing. Depending on the rock's color, the gauge goes faster and faster every time. After that then Tamako challenges you to punch rocks under a strict time limit before you can Net Battle her in the tournament. Aside from the precision needed to break them, MetalMan can and will teleport freely to anywhere he wants, while you have to walk instead. And once he gets to the rock he wanted, you cannot break it and have to find another one nearby. Even worse, this part has 3 rounds you have to get through. At least there's a break between each round. The only saving grace of this scenario is the reward, which is one of the most broken Soul in the series.
ProtoMan's (Blue Moon) and SearchMan's (Red Sun) scenarios. Both took place in the Undernet, which can only be accessed initially with the C-Slider (have fun looking for everyone involved with it!). This game's Undernet is THE hardest in the entire series, due to its very confusing layout and having some of the worst Demonic Spiders even by Undernet standards: CirKills (Moves fast and attacks the instant they are in the same row as MegaMan), Spidys (Invades your panel quickly and sometimes leaving damaging spiderwebs behind) and BomBoys (Pushes a bomb that explodes the moment it enters your side of the field, and it blocks direct projectiles). And the later areas of Undernet loves pairing these viruses together. This is not helped at all by the relative weakness of the chips available to you compared to the increasingly powerful enemies in this game. But that's not counting the scenarios. ProtoMan's involve a Pixel Hunt for a handful of "keys" that will allow Mega to proceed into the depths of the Undernet, which wouldn't be too bad if not for the Undernet thing and "Blind Idiot" Translation for the key location hints. SearchMan has you scour the Undernet while avoiding a sniper that deals a huge amount of damage when hit. All while the random encounters are still on.
Several NPCs will offer the player a hard-to-acquire chip, but only if they have a chip of a particular code to trade for it. Sometimes the chip of that code can be easily obtained through the Order system, or is part of a Chain of Deals that eventually lead up to something worthwhile. When this isn't the case, it's usually a rare encounter in the Bonus Dungeon that requires a high busting rank to attain. Get good and lucky with virus busting, or ridiculously lucky with the Chip Trader.
Obtaining every single chip in the chip folder can be a bit of a pain depending on the chip. Usually, you can get a greater part of them by playing the game normally, and a few require some specific grinding for... And then there's the ones that flat-out require manipulating the RNG of the game through the chip folder and enemy actions to even have a remote chance of getting. Don't feel like having to grind for specific chips and performing every action flawlessly? Well, hope you like them being a Luck-Based Mission from the chip trader then! Some of the most infamous ones from the first game include Howitzer and Dropdown.
Some of the chips needed for Library completion can only be obtained from Bug Frag Traders. What makes this difficult is that Bug Frags are painfully scarce most of the time. Delightfully averted in 3 where one can get Bug Frags easily from defeating enemies when they are about to attack.
"Legendary Tomes" in Battle Network 3 feels like a rather straightforward fetch quest, but in addition to the client's given reward, the quest gives a few vague hints on how to decipher the tomes you've been collecting to obtain the treasure (which is a ridiculous amount of money). Which is fine and all, but the results from deciphering the tome were not translated at all, turning finding said treasure into a bit of a Guide Dang It for those wanting to get the most out of it. If you turn in the quest without looking for the treasure, it's Lost Forever.
The Time Trials in Battle Network 3, available after beating several Bonus Bosses and needed to 100% the game. You have to beat the v2 version of every boss within a certain time limit, but you're restricted to an Extra Folder, a weak uncustomizable folder that you can get off certain NPCs in the game. Many of them are clunky and not as fluid as you'd expect of an endgame folder, making getting those times a daunting task bordering on Luck-Based Mission.
Anything that gives you a key item in Battle Network 4, most notably the C-Slider and Nebula Code. Both cost a non-trivial sum - 9,000 and 10,000 Zenny respectively - while involving backtracking to acquire them. Due to Battle Network 4's New Game+ structure, each time you start a new cycle, those items are not carried forward, needing you to spend more time and money just to re-open various areas of the net. The C-Slider even becomes mandatory for certain story scenarios as it is needed to access the Undernet.
"Self Research" in Battle Network 6 is a 2-star job available at least halfway into the game, and requires the player to complete a Program Advance and show the record to the NPC. Said components of that Program Advance involve a Mega Chip found in the Bonus Dungeon and a chip only available from a Bug Frag Trader. And the reward for this is a Number Code for a Navi Customizer part that only works in multiplayer matches.
The Virus Battler minigame in Battle Network 6 first involves you needing to go out and hunt down rare versions of viruses (which is a Luck-Based Mission on its own) to be able to use their data in the actual minigame. Completing this series of minigames is required for Library completion. When you do get to the minigame, however, you discover several elements that make it needlessly frustrating:
Sean, once-leader of Gospel. He only appears once again in the series after Megaman Battle Network 3, as a competitor in Battle Chip Challenge.
Mamoru, administrator of the Undernet, and Serenade as well, for that matter, never reappears after the third game.
Zero, the Battle Network incarnation of the franchise's greatest Memetic Badass. At the end of his own game, he decides to go wandering... and never reappears.
Ironically, even sometimes Scrappies Roll and GutsMan go wasted due an ironic failure to connect ideas between games. Battle Network 5 indicates healing powers are uniquely qualified to negate dark power, and Roll's special move "Roll Arrow" specifically destroys battle chip data; by rights, that should put her in a unique position to counter anything even remotely connected to Nebula. Meanwhile, the Secret Boss version of GutsMan in Battle Chip Challenge (look for his BCC code in Battle Network 4) employs a strategy entirely based around using powerful chips that require holes in the ground — Geyser, Old Wood, Magma Dragon, and God Stone. If he used those chips in the main series, where one of his specialties is putting holes in the ground, he'd be terrifying.
Operate Shooting Star features a time-traveling villain and a cross over with the sequel series, Star Force... for one scenario that basically amounts to playing tag. Otherwise it's just a port of the first Battle Network with a handful of new features.
Battle Network has more than a few Navi incarnations of reploids running around. We could have had Zero make an appearance in Battle Network 6, interacting with Colonel and Iris.
Values Resonance: Put yourself in Sean's shoes for a moment - There's nobody around you can relate to, you're stuck with cruel relatives (In his case, because his parents died), and the only people who you can relate to are online. Over ten years after the game was made, this still holds true to many people across the world.
One of the series recurring themes is cyberterrorism. While not invented by this particular series, Battle Network demonstrates objects being hacked and putting people in danger, government databases being hacked by terrorists, remote-controlled weapons going haywire, and crimes being ordered across the world with only the push of a button. In the 2000s, such a concept was still being thought of as fantastical. In The New Tens, technology and the Internet have developed to such an extent that many of the attacks depicted in Battle Network became reality (corporate & government databases now get hacked on a large scale at an almost annual basis), and cyberterrorism and cyberwarfare are constantly discussed in the media and by national security strategists.
A commentator has put this in an unusual light: In the 2000s, the series was a rather Saturday-morning cartoon esque series and made for great Snark Bait due to the obvious stupidity of adults. Unfortunately, ten years later, now many of the events within the series are plausible. Nobody's laughing now.
In the fifth and the sixth game there is a random fat NPC that stood out among others (there's usually only one or two of the kind) and can pass off as either a guy or a girl mostly caused by said NPC's pink shirt, hair curls and lipstick-like mouth. It was eventually revealed from some dialogues that the fat NPC is actually a guy.
Villain Decay: ShadeMan. After being gunned down by a Pile Driver in a postgame sidequest thanks to Django, he went down from being an Invincible Villain that can only be damaged by Dark Chips to a rather easy boss, also demoted to the second Darkloid you face in 5 instead of just below LaserMan in the Nebula ranks. His chip code was changed from X to S in the fifth game (Do note that the chip code X is usually exclusive to Bass and other chips related to him).