What Team Catastrophe turned out to be; they didn't want to win so much as they wanted to just break shit, and they were Placido's Unwitting Pawns to boot. Heck, Hans didn't even get to duel! This was due to Real Life Writes the Plot regarding a high number of car crashes in Japan at the time.
Sephylon the Ultimate Timelord, Z-one's trump card. It can Special Summon as many of his Timelord monsters from his hand, Deck, or Graveyard as he pleases, turn their ATK into 4000, and then let Sephylon gain their combined ATK. Thanks to Yusei's Ass Pull protag powers, it doesn't see the End Phase of that turn.
Arc Fatigue: The World Racing Grand Prix tournament. It consumed two-thirds of the series by being set up in the 3rd arcnote actually called the Pre-World Racing Grand Prix arc and taking place entirely in the 4th, where it's preceding 2 arcs had their own stories. Another problem is that it didn't need to take so long and was paced terribly: from Episode 98 to 129, many duels took five or even six episodes to complete. Also factor in the duels quickly got very formulaic and predictable with Yusei always being the one to win it for the team, and this arc just got tiresome.
Ass Pull: This isYu-Gi-Oh!, so there's guaranteed to be a lot of come-from-behind victories revolving around cards that had never been foreshadowed.
Rubble King from Episode 10, a card whose effect depends on there being a lot of cards in the Graveyard... and it just happened to be the second-to-last card in Yusei's deck. This card was created out of whole cloth to enable Yusei's victory in that episode and never appeared again, not even being released in real life.note Admittedly, the card wasn't his but belonged to one of the Facility inmates. And, technically speaking, he didn't even need it in the first place; he could have activated his winning trap card, Blasting the Ruins, at the start of his opponent's next turn.
From Episode 136, Ghoul Summoner. Its first effect is basically Call of the Haunted, but only for Synchros. Not so bad. Enter its second effect — as many times as you like each turn, you can Special Summon a Synchro Monster from your Graveyard, then take damage equal to its attack. Yusei revives Black-Winged Dragon and then revives Scar Red Nova Dragon and Shooting Star Dragon, using Black-Winged Dragon's effect to protect himself. Not only is this card absurdly overpowered, but it's worded in a way that its drawback can be negated (most cards like this make you pay Life Points specifically so loopholes like this can't be done).
Awesome Ego: No one is going to stop Jack Atlas! The fans love his immense ego.
Zigzagged with Aki. At the start of the series she was a stone cold bitch who nobody messed with, lest they suffer from her unleashing the powers she had. During the lead-up to the WRGP she was a moe school girl who did almost nothing plot wise. In the WRGP itself she's racing and dueling with the whole team... but loses in two turns in her only showing. She finally gets some badass creed back when Team 5D's heads up to Arc Cradle, where she teams up with Crow to soundly beat Sherry... but even then, Crow's the one to do the final hit.
Jack started to suffer from this, but then pulled off a wonderful subversion. While in the first season he was Yusei's equally-matched rival and the secondary main character, he gradually decayed until he became a Plucky Comic Relief at worst and a Memetic Badass bearing no relevance to the plot at best. A mini-arc addresses the perceived decay, with a robot duplicate of Jack's King persona claiming that the real Jack has lost his edge and couldn't win against his past self. After losing once, Jack has a rematch and whoops his doppelganger's ass in spectacular fashion. Another mini-arc saw Jack fighting against the forces of the Crimson Devil, where he steals its powers to make his newest trump card, Scar-Red Nova Dragon. It's also revealed that he's the reincarnation of a legendary Signer with a special power called "Burning Soul". It's implied that, without the legendary Signer by its side, the Crimson Dragon was losing against the Crimson Devil, which could mean that Jack is stronger than the Crimson Dragon itself. By the final episode he's turned himself from a self-proclaimed covered-by-money king into a real king, with only Yusei as his competitor for the position of strongest Signer.
Crow. It's hard to find enough people who share opinions to come to a consensus on what they think he is and what he should be. Some people call him the Kamina of the series (though most detractors say that the honor should go more to Jack). Others love him for what he is, the Large Ham of the cast. Still others cite his status as a walking ad foran overpowered set of cards, his lack of significant losses and weak duels, the fact that he became a Signer, his personality being seen as redundant in the group and uninteresting overall, and the fact that he never shuts up as reasons for being hated. This extends to just about any episode that revolves around Crow, to the point where, if you see Crow featuring prominently in an episode, there's bound to be an argument about it.
Kiryu became one with Crashtown (prior to it, he'd been quite popular). Maybe it was that he put the plot on hold for another six episodes in a season already mostly filler, maybe it was the fact that his new Deck was a complete Game-Breaker, maybe it was because he essentially wrote out non-Team Satisfaction characters from the arc in a season that had already been bad for them, maybe it was because certain elements of his backstory got retconned... All these things either made people love him even more or turn their backs on him in droves.
Bruno. Despite some people find that he's a little hard to believe, a lot of people love him after his true nature has been revealed.
Better on DVD: Especially when filler episodes can be skipped over and some, like Crashtown, can be treated as a bonus arc.
Let's just say that the only thing that the fandom can generally agree on is that the music is great and the first 64 episodes were better than what came after that. You'll have arguments on anything from how many seasons exist to correct character spellings to anything involving Aki and Crow.
The chants everyone performs when they Synchro Summon, which would become a trend for later series when summoning Extra Deck monsters. Are they cool, or just a waste of time, especially after you keep hearing over and over again?
Crashtown Arc - pointless filler that ran on for too long and changed absolutely nothing, or interesting arc focusing on a character that until now had been Put on a Bus? The fans may never agree.
As of Episode 107, Placido's transformation. The coolest villain in all of Yu-Gi-Oh!, or just silly?
Z-one's true identity- a good plot twist, or poor writing after foreshadowing pointed to something else?
Divine/Sayer, is the leader of a group of Duelists training to control and harness their psychic abilities in order to turn them into soldiers of war against the rest of humanity. His earliest Duelist, Toby Lola/Toby Tredwell, was unable to withstand the procedure meant to test his abilities. Believing him to be weak and useless, Divine ordered the intensity of the electric shocks to be amplified, causing the young boy's death. He also does his best to keep his prized Duelist Aki Izayoi secluded from anyone outside the Arcadia Movement to keep her full of hate and resentment at the world for his goals, as well as to hide his own secret motives. To this end, he gasses Luca, Lua, Yanagi and Jin Himuro when they come to him for aid against the Dark Singers. Then he threatens Lua's life in a Psychic Duel to test if he has powers like his twin sister Luca. Later that day he has another Psychic Duel with and murders Carly Nagisa by sending her through a window with a direct attack, beginning her rebirth into a Dark Signer. He then returns from his Disney Death at the hands of Carly, posing as a security agent to attack Yusei and Mikage Sagiri. Divine states that anybody who falls prey to him will simply follow his orders and nothing more, as he takes full advantage of that individual's weakness, just like he did with Aki.
Lotten/Lawton, is a tyrant lording over a small western style town called Crash Town, where he forces those he's defeated to join him or face slavery in the mines. He gets into a match with Yusei while Yusei and the gang are trying to escape the mines, but before it can be decided, he throws a stick of dynamite at Yusei, Kyosuke Kiryu, West and Nico that results in a cave-in; Yusei and Kiryu fall off the mountain, while Nico and West are unconscious on the ground. Lotten takes them back to Crash Town, renaming it Lotten Town after Barbara and he double-cross his brother Malcolm. Later, not satisfied with the number of workers in the mines, he and Barbara begin forcing their henchmen to Duel for their survival, which is stopped by Yusei and Kiryu. Once he does start to lose his 2-on-1-handicap match against Yusei and Kiryu, he quits the Duel and tries to run away, but not before he abandons Barbara to her fate and sets off explosives in the town.
Kiryu, thanks to the fact that his Laughing Mad tendencies rivaled Yami Marik, and were well-received in both versions and for being an extreme badass. He also introduced the game to the powerful Infernity archetype. The fact that he obtained a seven episode long arc focused on him may or may not be acknowledging his fan popularity.
Carly, thanks to her relationship with Jack and being Adorkable in general. Shippers wanted to see more about it. They did not appreciate her demotion to extraat all.
The Familiar of the Crimson Devil is quite popular as well, mainly due to his quirky personality, though it also helps that he was in an arc that was well-received for having Jack Take A Level In Badass.
Cup Ramen Man.
Martha, the foster mother of Yusei, Jack and Crow is unbelievably nice, despite having lived in Satellite her whole life, even to then-at-the-time Jerkass Ushio and former betrayer Jack.
The whole of Team Taiyou, who were so utterly likable that most fans ended up rooting for them in their match against Team 5D's. Their usage of classic Normal Monsters from the game's olden days really earned them a lot of points in older fans' eyes. This ended up applying in-universe as well after it was revealed that they were trying to summon an almost un-summonable-monster.
Nobody in the entire fandom seems capable of hating the MC, whose ham is absolutely glorious in both the original and the dub. He even stays behind to commentate on Yusei's duel with Z-one!
Card wise, Yusei's Fusion Monster, Dragon Knight Draco-Esquite is rather notable due to being a sensible answer to his Machine Emperor Synchro Killer issue. Sadly, it's also a One-Scene Wonder.
A 2018 popularity poll showed Black Rose Dragon to be the most popular monster in the series, beating out Stardust Dragon and all its upgraded forms by over a thousand votes. Its unique design, powerful abilities, and being used by the likely most popular female character in the entire franchise all account for this.
Mukuro Enjo/Hunter Pace is also fairly popular: It helps that he is one of the few characters from Neo Domino early in 5D's who is not particularly villainous, jerkish, and he is pretty funny in both versions. Fans were pleased to see him cameo again in ARC-V, even if it was just to get beaten by Shun Kurosaki/Shay Obsidian.
Several, but one that sticks out is the thought that Rudger is Jack's father. Or that Godwin is Crow's father. Interestingly enough, in the 5D's manga, Godwin is Jack's adopted father.
Sly is Divine's son.
Zone is Yusei's future self. While the theory was Jossed, given the known level of Executive Meddling in other parts of the show, it's been theorized this was the intent originally, but the showrunners weren't allowed to do it and had to change their plans.
Many people theorize that Yusei is now dead thanks to his final shown stunt of jumping over the bridge connecting Satellite and Neo Domino. It doesn't exactly help that Yusei already dodged huge air fans, jumped over a pit of magma, and stood on top of a cliff's railing in the final episode alone.
Rua/Aporia has quite the backing, especially once Aporia showed up to duel Z-One.
Jack's fangirls, Mikage, Carly and Stephanie.
Stardust Dragon and Red Demon's Dragon. Most fight scenes between them are portrayed rather harshly, yet they have no problem working together when necessary.
Fridge Brilliance: Some fans wondered why Yusei needed to find Accel Synchro when he already had Savior Star Dragon. But watching the Yusei vs. Placido duel, it becomes apparent that Placido had already found a way to counter Savior Star. Savior Star Dragon can negate one monster effect per turn, but stealing the Skiel Carrier cards gave Placido two lines of defense (Wisel Guard 3 and Skiel Carrier 5). Savior Star would negate one, bounce off of the other, and get absorbed the next turn. Game over, hero dead, town destroyed, roll credits. Jury's still out on Turbo Warrior, though.
Quite literally. Crow somehow stopped himself from being sacrificed to the Earthbound Immortals by hiding in one for around twenty-four hours! This happens once again when he avoids being killed by jumping into a fridge with an old man.
This bit is exclusive to the English dub. Jack, Yusei, and Crow grew up together in the same neighborhood, ever since they were babies. And yet Jack is the only one with a Cockney accent.note Though even in the Japanese he has a distinctly English name and appearance in comparison to his friends.
Yusei is looking for a card that can defeat the Emperors... preferably a Synchro Monster... a card that can ignore the effects of monsters (low-level ones, if that's important)... a card that fits into his Deck strategy, and preferably his Deck... Nope, ain't got nothing like that!
Similar to the many references to real-life subjects hidden in Yu-Gi-Oh! GX, the Fortune Cup and Dark Signers arcs are full of references to Incan mythology, while the W.R.G.P. arc gives us references to geneticists, genetics, and biology.
In Bonds Beyond Time, when Malefic Paradox Dragon is destroyed, Paradox activates Malefic Paradigm Shift to summon Malefic Truth Dragon. This emulates the progression of philosophical and scientific knowledge: a contradiction (paradox) forces the thinker to reconsider the whole system and propose another general explanation (Paradigm Shift) to achieve true knowledge (represented by Truth).
Z-one's Timelords started a trend of the franchise referencing the Sefirot. Z-one also summons each Timelord in its order on the Sefirot, and when he has multiples on the field, attacks in that order too.
Lucciano is nucking futs, a Laughing Mad child psychopath, and a Large Ham if there ever was one. It gets a bit hard to mock him for it after realizing that he represents a child who was driven insane by the loss of his parents.
Straighter example: Zero Reverse and the Bad Future itself, thanks to Japan suffering what is pretty close to the real life equivalent with the 8.9 earthquake, tsunamis, and power/nuclear plants exploding.
Carly's role as a Dark Signer when it was eventually revealed that her original voice actress was fired when it came to light that she was part of a cult.
About a month and a half prior to the series airing, Yu-Gi-Oh! The Abridged Series had Tristan ride up on a motorcycle, and when asked he explained that "in the future, card games will be played on motorbikes," before cutting to a promotional artwork for 5D's. Then the series got dubbed, and who should be voicing Yusei but the same guy who voiced Tristan, using almost the same voice he did for Tristan too. Hilarity ensued.
Some fake episode titles mentioned something about a new Earthbound Immortal. With the airing of Episode 112, we learn that the Crimson Devil is actually an Earthbound Immortal that fought one-on-one with the Crimson Dragon and lost. Said immortal was based on a serpent Nazca Line, which wasn't known to exist at the time. In 2014, an actual snake Nazca Line was discovered.
Early in the series a few people speculated that Power Tool Dragon might be a Signer Dragon as well. However, most fans were quick to point out the inconsistencies if such were to be true (such as it being a Machine-type). It was also pointed out constantly in the show itself that Rua couldn't be a Signer, a notable example being a recap episode in the WRGP story arc that also stated the previous point about the dragon's typing. Cue Season 2, after the rumors were already long dead, where it turns out that Power Tool Dragon was actually a dormant form of the final original Signer Dragon, Life Stream Dragon, along with a new Signer mark introduced almost completely out of left field.
In the original Japanese version, Misty's grudge against Aki stems from the idea that Aki is responsible for the death of Tobi, Misty's younger brother. One of the characters Misty's voice actress Junko Minagawa is also known for is Cornelia li Britannia, who despises the Black Knights and, more specifically, Zero for the death of her brother Clovis, and later, her little sister Euphemia. It gets even better with the numerous comparisons of Aki to Kallen visual wise, as Kallen is a leading member of the Black Knights, and hates Britannia for killing her older brother Naoto. Looks like the bad blood between these two spans different series.
Macekre: While 4Kids put some effort into their dubs of Duel Monsters and GX, by the time they got to 5Ds, they had given up. There are numerous Dub Induced Plot Holes, a lot of card effects are misstated making duels hard to follow, there are radical shifts in characterization and backstory, several episodes were completely cut introducing more plot holes, and the entire final arc with Z-one was removed to make Aporia the last enemy, leaving Z-one's fate a case of What Happened to the Mouse?. Tack onto all that the typical cases of Bowdlerise and VERY cheesy Adaptational Comic Relief (which is used in scenes that were treated as serious in the Japanese version) expected from the company, and the dub of 5Ds is a total mess.
Magnificent Bastard: Rex Godwin is the head of Security and a member of the secret society of Iliaster. He rose to this position after being stranded and forgotten in the slum of Satellite, and has single-handedly turned Neo Domino City into a classist technological utopia under his control. Using his power he begins gathering the prophecied Signers and awakening their powers, then presents himself to them as a mentor and benefactor who would aid them in their war against the Dark Signers led by his brother Rudger. However, Rex is playing both groups against each other to make his own play for power, allowing Roman to kill him so he can become a Dark Signer, and then using Roman's severed arm bearing his Signer Mark to make himself a Signer. Transforming himself into a Yin-Yang Bomb with the power of both groups, Godwin seeks to destroy the world and remake it in his image, and almost succeeded if not for The Power of Friendship overriding his willpower to force the Signer marks to obey him.
Nitro Warrior. Nearly everytime it's summoned, the opponent is OTK'd - in Crashtown, Yusei summons Nitro Warrior and OTKs three guys at once!
Jose. He runs down the track after Jack's D-Wheel when it's his turn marks to duel, and keeps up with him until he merges with his D-Wheel a few moments later. Many jokes ensued about the possibility of him just running around the track for the duel without a D-Wheel, which apparently he could have.
Memetic Molester: Aki - a lot of people make jokes about how her usage of Rose Tentacles on Yusei was a little too suggestive.
Yusei's poncho. It only shows up in the filler Crashtown arc, but is very well remembered by fans. Becomes an Ascended Meme of sorts where 'Poncho Yusei' is its own storyline in Tag Force 5.
One Turn, Three Kill, originating from a duel in the Crashtown arc where Yusei defeats three opponents in one turn, prompting said line in Engrish from a stunned onlooker.
End Your Damn Turn, Jean became popular after the notorious duel in the WRGP where Jean could literally have defeated Yusei by ending his turn (Yusei would have lost by deck-out if he had, but Jean attacked instead and lost as a result).
The Twitch Marathon spawned a few new memes.
"Thanks Siri", in reference to the computer voice that details what certain cards do in the dub.
Referring to any members of the cast as someone from a previous series. "Tristan" for Yusei, "Bakura" for Jack, "Atem" for Trudge, and "Jesse" for Crow are some examples.
Lazar is referred to as Frieza due to being short, having a British accent, and generally acting like a pompous scumbag.
Continuing from GX, everyone is once again Goku. Greiger, like Viper before him, is referred to as "Goku Black".
BUY BLACKWINGSnote Many fans know the Executive Meddling involved with Crow just to sell Blackwings thus this will come up while Crow is dueling.
Bootleg Graceful Charitynote The Speed Spell - Angel Baton, a card that nearly every Turbo Duelest plays akin to Pot of Greed, is a Spell Card that allows the player to draw two cards and discard one. Its effects are similar to Graceful Charity thus the comparisons were inevitable.
Misblamed: Zig-Zagged with Crow. Yes, there was pressure from Konami to push forth the popular and useful Blackwing monster archetype. However, there were lots of issues behind the scenes regarding casting issues from the female leads (in Aki's case, her voice actress simply wanted time for her marriage, which forced them to reduce Aki to a side character) forced the hands of the writers to make Crow a more prominent lead character.
Cup ramen is a major plot point in a couple of episodes. The plot becomes downright ridiculous when Yeager's mother sells her prized show dress to buy cup ramen, and then ramen drives his backstory Off the Rails.
Team Satisfaction as the name of a vigilante dueling group. LittleKuriboh had fun with that in his 5D's parodies.
Let's just say that Placido was more intimidating riding his D-Wheel than becoming his D-Wheel.
Older Than They Think: The idea that Duel Disks can be used for communication, which many credit for the D-Gazers in Yu-Gi-Oh! ZEXAL, actually appeared first in this show as a plot device in Yusei's Duel Disk as a way for him to clear Aki's name for her involvement in Toby's murder by tricking Divine into admitting it and broadcast it to Misty. Yusei is actually shown using this ability earlier to communicate with Saiga, although the Duel Disk is connected to his D-Wheel at the time. It's also logical to assume that this ability is used constantly in Riding Duels as otherwise it would be impossible to hear your opponent.
Periphery Demographic: While the series is targeted towards young boys, it has also attracted an audience of roughly women aged 13-26 thanks to the Ho Yay and watching the original series as children.
Popularity Polynomial: While the second season was running, many fans turned against the show due to the season tripping a large number of stumbling blocks including but not limited to retcons, characters being Demoted to Extra, pacing, and excessive Product Placement (though the last arc of the season was considered better than the first two). Several years after the series concluded, however, stories began to creep out detailing an absolutely tremendous amount of external pressures the writers were forced to contend with, leading fan opinion to turn back in their favor and even commend them for still managing to resolve everything despite the extenuating circumstances. Finding 5D's listed as the second-best series to the original nowadays (or even better) is quite common.
Adding in Bruno to replace Kiryu for a new four-man group in Season 2. This lessened somewhat when more emphasis was put on Bruno being a Sixth Ranger to Team 5D's rather than the fourth member to Yusei, Jack, and Crow specifically.
Crow himself for replacing Aki's status as the third-billed hero. Right after the YGO franchise (notorious for its girls being either Faux Action Girls, Scrappies, or both) finally managed to give the audience an interesting, sympathetic, badass and plot-relevant female human character who has a rather large fanbase! Not help by accusation of being a Creator's Pet. Even after being rescued, he still never achieved Aki's popularity during the first two arcs.
Who is a Scrappy in 5D's varies almost depending on who you ask. However, every fan seems to agree that Leo/Lyndon* Zora's son, not Rua's dub name from Episode 85 is an absolutely terrible character.
Seasonal Rot: After the Dark Signer arc, the series heads downhill. Character sub plots are forgotten or go nowhere, numerous supporting characters are Demoted to Extra or just written out entirely without mention, a lot of established backstory is Retconned, and the WRGP Tournament Arcdragged and ultimately had little purpose beyond advertising. With that said, the final Arc Cradle arc is considered a massive improvement over the rest of season 2 (though still not to the highs of season 1), with entertaining duels that have real stakes, tragic and relatable antagonists, and the writers finally remembering to give Rua his Signer Dragon after leaving that plot thread dangling for 90% of the show. When the story of the season's Troubled Production broke (see the Trivia section), many fans became more forgiving of it and praised Arc Cradle for actually managing decent resolution under severe extenuating real-life circumstances.
Shocking Swerve: Z-one not being Yusei, despite sharing the same appearance and heavy foreshadowing.
While his plan to destroy an entire city was undoubtedly drastic, Z-one is the last human survivor who was trying to prevent the same thing happening to the whole world. Team 5D's fights against his plan without even trying to think up of an alternative way to prevent the apocalypse besides a generic hope speech.
Yusei himself becomes a rare instance of a protagonist being reduced to a strawman. His idea of trying to duel without Synchro monsters in preparation for the Machine Emperors makes sense, since they get stronger by absorbing the enemy's Synchro monsters, but he gets laughed off as cowardly by Jack, who goes on about power without offering any alternative to fighting the Machine Emperors, and then gets introduced to the concept of Accel Synchro soon after. This might have been intentional however, as the series promptly proceeded to deconstruct Jack's power strategy.
Aki. During the first arc, she was instantly popular due to her creepy powers, tragic backstory and for apparently being the one female character in all of Yu-Gi-Oh! to not be a Faux Action Girl. Then she was replaced by Crow during the climax of the Dark Signers arc and remained Out of Focus for the rest of the series, especially when compared to the three male leads. While she did get a small subplot leading up to the WRGP, the only plot-relevant duels she took part in during the second half of the series were the one against Team Unicorn (where she ultimately lost along with Jack to give them a leg-up), and the one where she was teamed up with Crow against Sherry. To say that this disappointed fans would be an understatement.
Ruka as well. Her spiritual connection with the duel monsters all but outright stated she was destined to play a major role in the series, but she never really went past the point of being the Kid-Appeal Character. It doesn't help that, despite her signer dragon being tailor-made to counter the dark signers, she was pushed to the sidelines for most of the arc.
Aki's character arc in the second season began with her wanting to learn how to Riding Duel to understand the adrenaline and energy that Yusei and other D-Wheelers feel, and it was hinted she wanted to get closer to Yusei after being jealous of female D-Wheeler Sherry. Once she actually got her license to ride Aki only ever took part in a single Riding Duel as a member of Team 5D's, and was eliminated in the same episode she went in. The same thing happens to Rua and Ruka; when they get a two-episode arc involving them Riding Dueling using skateboards instead of motorcycles, it goes absolutely nowhere.
Speaking of Ruka, her first real focus episodes suggested a creepy, psychological, Fair Folk-ish take on the Spirit World and that she might have a major role to play. Then in its next focus episode in the Dark Signers arc... we get an absurd plot about monkeys and minus rods that couldn't be more at odds with the earlier story, in a battle with a villain who has literally no backstory. And then the whole concept is never mentioned again, and Ruka's status as the Spirit World's protector is completely forgotten and she never does anything for the entire rest of the series.
After all the focus on Jack and Carly's relationship during the Dark Signers arc, the dreaded Reset Button rears its shiny head. Their relationship is never put into focus or developed in any form or shape again, and instead Carly is reduced to being just another Jack fangirl for the sake of comic relief. The sound you're hearing is the sound of Jack/Carly shippers reaching for the torches and pitchforks.
Divine and the Arcadia Movement reek of wasted potential, especially since, with the exception of Aki, Psychic Duelists were never really brought up again once they were gone.
Jack's and Yusei's scarred friendship was one of the main focuses of Season One (and the entire focus for the first five episodes), but it was never fully explained what happened that caused them to grow so far apart after Kiryu's death.
When Sly, one of Rua and Ruka's classmate, was introduced, the series made notice that he had interest in Yusei's Stardust Dragon and wanted it for himself. This was never developed.
Yusei using Fusion was a heavily built-up plotline (by some accounts foreshadowed all the way into Bonds Beyond Time), it made perfect sense to Break Out the Museum Piece, and many fans appreciated the acknowledgement of a mechanic that Konami had previously been doing their best to bury. He uses one Fusion monster in one duel, and not even against the people it was meant to defeat, before he solves the problem of an anti-Synchro strategy through a simple Next Tier Power-Up.
The Familiar was an incredibly fun character, and his boss, Scar Red Nova, had a lot more to do with the Signer's lore than the Emperors and seemed a very legitimate threat that could have easily carried the season. They only show up for a two-parter, and their only relevance to the plot was giving Jack's Dragon an upgrade.
A lot of Foreshadowing went into hinting at Z-One being Yusei from the future. When it was revealed that he was just some random nobody who underwent plastic surgery to emulate Yusei, the fandom went nuclear.
Rally. Someone really needs to tell that kid that he dresses like a girl, and the long fluffy hair doesn't help either. This is even lampshaded in Tag Force 4; when Carly tries to question Yusei about his life, Rally forces her and the player character into a duel. Carly whispers to herself, "What is with this girl!? She's cute, I'll give her that, but..." to which Rally angrily responds, 'I'M NOT A GIRL!!!'. Carly completely ignores this and continues talking to herself about accepting the duel.
Jaeger fits the trope, too. Lampshaded in Episode 81, when a holographic Jaeger "clone" can't make up its mind about whether it belongs in the men's or ladies' bathroom.
Lucciano has a long braided ponytail, eyelashes, and a feminine voice. But at least he wears the male school uniform.
Season 2 and onwards got, and still gets, a lot of flak from the fandom, but many have become kinder to the series since its behind the scenes issues were revealed.
Z-one has received a fair bit of this as a Final Boss due to the following ones (the much-disliked Don Thousand and the controversial Zarc) being seen as a step down (and the previous one, Nightshroud/Darkness being regarded as a heavy case of an Anti-Climax Boss). His Timelord deck also plays significantly into this, as the deck is playable in real life both physically and competitively.
Aki's backstory. Can be justified by the fact that she is only about 12-14 at the time and 16-17 during the series, makes it (somewhat) Age-Appropriate Angst. And being overly dramatic is somewhat expected of a teenage girl anyway.
Yusei's on-again off-again fear of Machine Emperor Wisel, an Anti-Synchro monster that he's already defeated. Using a Synchro Monster (admittedly it was a Deus ex Machina moment, but still...)
Woolseyism: While the dub of 5D's is lacking in comparison to the original Japanese version (as listed in Macekre), there are some that think the dub may shine, depending on who you ask:
Turbo Duels and Duel Runners in comparison to Riding Duels and D-Wheels (the latter name really only suits Jack and Bruno's).
The English dub's "Earthbound Immortals" just sounds more dramatic than the original "Earthbound Gods". There's also a similar instance of renaming the "Polar Gods" to "Aesir" in the dub/TCG. Aesir is a group of gods that Odin and Thor belong to and which Loki is heavily associated with, despite not actually being one himself.
A notable instance is changing Himuro's knife that he hid from the prison guards into magazines. The dub simply makes it more subtle and turns it into a Parental Bonus.
Due to Never Say "Die" the dub couldn't bring up Misty's brother's death, so the conversation about Aki's powers in their first duel changed from being about him to being about Aki's actions at the Fortune Cup. The Woolseyism part comes from Misty's Armor-Piercing Question of whether the crowd deserved to get hurt for mocking Aki and whether she actually just enjoyed inflicting pain. Her stunned inability to answer just emphasizes how powerful that question was.
Another one is that Aki in the dub is generally more emotional in her speech pattern than her Japanese counterpart, thus signifies her Defrosting Ice Queen arc and unintentionally made her feelings for Yusei more touching. This can be attributed to the fact that Aki's Japanese VA Ayumi Kinoshita has less experience in voice acting than her English one Erica Schroeder (Bella Hudson), as well as the dub having more lines for her.
Video game examples
Anti-Climax Boss: For a character touted as the King, Jack Atlas in WC 2009 is a pushover compared to the Sequential Boss before him, due to a lack of focus in his cards as opposed to the previous opponents' refined archetypes.
Big-Lipped Alligator Moment: At one point in WC 2011, the player is visited by a mysterious Turbo Duelist who tells them to "evolve their Synchro Summon" to stand a chance at beating the Meklords. While intended to parallel a similar moment in the anime between Yusei and Dark Glass, this ends up serving very little purpose as the player cannot reliably obtain the resources to do so, nor do they need to anyway.
Crutch Character: Due to being one of the earliest archetypes in the game's history, a Gravekeeper's Deck can be very easily assembled from some early packs, on top of being reasonably powerful when the field allows you to put out a 2000-ATK Level 4 monster. The archetype does dwindle in usefulness once the player gains access to the newer archetypes due to the game's inherent Power Creep, but it not being reliant on Synchro monsters helps dramatically with the lack of access to them in Stardust Accelerator, on top of the archetype countering three quarters of the game's infamous penultimate boss gauntlet.
Ensemble Dark Horse: Toru and Misaki (especially Misaki) from WC 2011. They're one of the few game-original characters in the WC series to be important and heavily fleshed out and make a great ¡Three Amigos! with the player. They also have unique decks with uncommon archetypes (Scraps and Watts, respectively), as opposed to some of the cookie-cutter decks most NPCs have.
The four clones of the protagonist in 2009 is the penultimate boss but is also easily one of the most difficult fights in the game. It takes the form of four Duels in a row while your remaining LP carries forward to each next one. While the first two decks may be moderately challenging, the third is a Lightsworn deck which was in its prime during the time of the game's release, and the fourth is a variant of the tournament-dominating Tele-DAD deck.
Dark Signer Bommer in 2010. A Turbo Duel is painful enough since the game introduces it not long beforehand, but you also must allow him to summon his Earthbound Immortal before you can win. Not helping matters is the mechanics of the Earthbound Immortals — their Achilles' Heel is a moot point in a Turbo Duel due to the un-removable Field Spell, and their inability to be attacked (on top of not allowing direct attacks if they're the only monster on one player's field) can bring a planned assault to a screeching halt.
Dark Signer Kiryu from the same game could count during the first time you face him in story mode. Facing a boss playing an Infernity deck when both players start with no cards in hand is a nasty challenge for the unprepared. Though he can become a Breather Boss if you run a pure beatstick deck; being limited in draws means he can't build up any sort of counter.
Dear God, Lotten in 2011. He starts with ten cards in his hand and runs pure burn. Do the math. Sometimes you need a miracle not to be killed on the first turn. Not helping matters is that it's a Tag Duel, and if you go second, Kiryu takes your team's first turn, and his AI might make matters more difficult.
The stealth missions of sneaking past Security. This was a pain to complete in 2009 and they mercifully toned it down in 2010.
The "battle" against the Ghosts in Over the Nexus, thanks to an Unexpected Genre Change to Bullet Hell. Better hope you've been keeping up with your D-Wheeler parts because without a decent amount of health and good maneuvering ability you will be destroyed and have to start over.