Angst? What Angst?: Yoh, who ends up being revealed as a deconstruction of this as long as the series goes on. There's rarely something that seems to bother this guy, not even being killed (so that he can get some literal Training from Hell, though he wasn't informed of this beforehand). Except that time when Faust vivisected Manta, who at that moment was his only friend. But, as it's shown in volumes 19-20 where he wants to cure Anna of her Emotion Bomb powers and make Matamune a new Over Soul so he could never see him again, he is more of a Stepford Smiler.
Anti-Climax Boss: Several. Most notably near the manga's end where the end of the Patch officers' battles are skipped.
Lyserg is another big one where some forgive his trespasses, and others do not.
Anna is probably the biggest one, as while some love her, others despise her for her abusive jerkass tendencies.
Hao gets this too. There are those who like him and those who do not. The ones that don't like him are due to being an overpowered villain (especially in the manga), hypocritical, having a arrogant Social Darwinist type attitude, and a Karma Houdini in the manga. Even with his back story in mind, these fans feel it doesn't excuse Hao's actions. In fact, the list described from before makes some fans see him as a more unsympathetic person.
Manta. Some fans consider him a good Foil for Yoh and Token Muggle (before being Demoted to Extra), while others see him as the annoying sidekick because he always reacts by freaking out.
The anime changing events from the manga. Half of the fans prefer the anime's finale because Hao gets his Karmic Death, while the other half loathes it because they feel it distorts the real intention of the manga and transforms Hao into a standard villain with no sympathetic qualities. On the other hand, the manga ends with letting Hao become Shaman King and the knowledge that he has only temporarily postponed his annihilation of the human race, giving a wait time during which humanity must prove it is worth its existence, and one could argue that the ending implies it can't, any and all parts of which can be understandably hard to swallow. More was eventually added on to the manga's ending in additional spin-offs but they failed to cool the controversy.
Lyserg's story arc in the anime. While some people are fine with this, many vocal fans hate that Anime!Lyserg is willing to betray Yoh and his group because he put his revenge above his friends, even to the point of abandoning Morphine in favor of the X-LAWS angels. On the other hand, the manga portrays Lyserg in a more sympathetic way: He still remains friendly to Yoh after joining the X-LAWS and outright says that he would never abandon Morphine, since she is the only family he has left.
Fans of the manga were NOT pleased that the anime skipped most of Luchist and the other members of Team Hao, since their backstories were also very important plot points.
The manga in general and whether it got worse or better in quality as the story went on. Proponents claim that the manga is a good example of Cerebus Syndromegone well, while detractors cite that characters became more unsympathetic and the plot pieces less well-constructedas time went on. It doesn't help that most of the planned character arcs and plot points were rewritten at different points throughout the manga's creation, causing some jarring Tone Shifts and Character Development in unexpected directions, which some theorize only happened due to the author's growing misanthropy.
The anime making Manta and Mosuke another Shaman-Companion Team. Half the base consider this a perfect pair for both Yoh and Amidamaru by having their best friends join the battle. On the other hand, other fans consider that giving powers to Manta misses the point by removing the only muggle friend, because his character was supposed to be the proof that humanity does have good people. Of course, it's not like the manga did this well either, considering it just dropped Manta's character arc entirely.
The manga pulling Death Is Cheap in a story about the serious relationship between life and death, which for some trivialized any of the risk the characters experienced in the first place. Especially since Death Is Cheap only pertains to main characters, and is conveniently averted for the people in any given character's past when the author wants to make them sympathetic. Doubly especially since, despite death being a serious consequence for everyone else, it's the go-to strategy in the plot to get main characters their power ups. On the defenders' side, this isShōnen. Essentially, the debate is over whether it was bad writing for the author to arbitrarily make death a horrific final sentence for unimportant side characters and a blatant cheat code for the main cast.
Creepy Awesome: Faust VIII is one of the most creepier shamans around, and yet his necromantic powers are some of the coolest you will ever see.
Dueling Works: With Hunter × Hunter. Both started publication the same year (with Hunter x Hunter predating it by three months), they both have a magic rule set that allows them to turn everyday objects into deadly weapons, and they both have the hero's friendly rival being a child raised by a family of assassins.
Ensemble Dark Horse: Faust VIII is probably the most popular in Yoh's team behind Horohoro and Ren, despite his relatively minor role in comparison. Helping his favor is his Creepy Awesome aspects, his unique fighting style compared to the other Shamans, and his tragic backstory.
To say nothing of Ryu's obvious feelings toward Lyserg, many of the guys fall into this. Notable cases being Ren/Horohoro, Amidamaru/Mosuke, Hao's devoted followers, and some subtext between Manta and Yoh. The omake introduces some with Lyserg and a new character, Hudson. Fridge Brilliance on the creator's part, especially if you've seen Guy Ritchie's Film/SherlockHolmes movies.
And special mention deserves to go to Marco and Luchrist, who both strip down to their underwear before fighting for the final time, due to that apparently being how they channel their power the most comfortably. The two used to be close friends in their backstory.
Jumping the Shark: As seen in Fanon Discontinuity and Seasonal Rot, many fans felt there was a specific point at which the story became more bad than good. The exact point this was is still debated among fans, but a few are mentioned in the discussions more often than others:
The "Princess Hao" moment, for trying to frame a genocidal maniac who's slaughtered thousands and intends to slaughter billions as a victim after arguably having failed to credibly make him sympathetic, and further, for trying to downplay the seriousness of his crimes by positioning him in a comically exaggerated damsel in distress role.
On a more ridiculous note, the "Ancient Aliens" moment, in which the author inserts the actual Ancient Aliens conspiracy theory into the world of Shaman King in the final arc of the story out of nowhere and then plays it 100% straight. It then throws in the Lost Continent of Mu and an alien technology conspiracy with the Patch tribe in there for good measure, reflecting, quite literally, the same amount of continuity relevance, logic, and historical understanding as this meme◊.
Magnificent Bastard: Big Bad Hao Asakura was once a shaman in heian-era Japan where he lost his beloved mother at the prejudices of humanity. Manipulating future events and even his own reincarnations to empower himself, Hao is reborn again in modern times as the twin brother of hero Yoh Asakura. Absurdly powerful and intelligent, Hao remains a step ahead of the heroes, defeating all challengers and enemies in an attempt to become the Shaman King and destroy humanity. At the end, Hao succeeds in his goal, becoming Shaman King, but proves open to reason and opts to watch the world for himself, being as brilliant a villain in victory as he was in the attempt to get there.
Moe: Quite a few characters, most of them male. Yoh, Lyserg, Manta, and (possibly) Chocolove probably fit this trope best.
Only the Author Can Save Them Now: The Big Bad was already the most powerful character in the manga's present day, but having the ability to reincarnate at will meant he could never be truly defeated. Each loss just means he had another chance to come back even stronger and possibly succeed next time. Hao giving up his plans to murder humanity is the only reason the protagonists "win".
Manga!Chocolove, since his character is fleshed out more after his backstory is revealed: He used to be a gang member in New York who killed mercilessly, until he met his master and reformed his life. But even after changing for good, he learns that his past will still haunt him, since one of the people he killed was the father of two kids who were trying to get revenge on him. It gets even better for his character after he Took a Level in Badass and actually becomes the strongest member of the Elemental Warriors.
Also Manga!Lyserg as well, since his loyalty towards Yoh and his family's memory remains intact, and also he becomes the Straight Man for Marco and Jeanne after most of the X-LAWS die and, in an ironic twist, he ends up getting The Spirit of Fire, since it would also help him deal with his hate towards Hao and keep his revenge desire grounded.
Even though she is more of a Base-Breaking Character since not that many hate her, Tamao also became this around Funbari no Uta and Flowers after her Character Development, to the point some resent that Flowers should have been about her instead of Hana.
Pirika, since many feel her character is useless and annoying.
Chocolove, for being a black sterotype and an annoying comic relief. The manga!Chocolove, on the other hand... see above.
Opacho, big time. Many felt that she was very pointless and only served to give Hao a Tag Along Kid.
Also, the X-Laws, particularly Anime!Lyserg for abandoning everyone (especially Morphine) and Marco for hitting Lyserg.
Manta sometimes is viewed as this, due to his character arc being dropped entirely once Cerebus Syndrome took affect, flanderizing him to basically Yoh's Muggle cheerleader. He's got an interesting relationship with fans of the anime, due to having more presence in the plot but ultimately still being useless until his One-Scene Wonder shot at the end.
Seasonal Rot: In the manga, after a hiatus. Instead of becoming more interesting, many found that characters (both heroes and villains) grew much more unsympathetic and preachy as the story went on and backstories were revealed. The fact that the manga ends on a condescending, defeatist note about the nature of normal humans and the future of humanity has caused some to even accuse the author of misanthropic ranting, given how little the manga actually does to refute Hao's anti-human views, and how, after the hiatus, the manga actually could be arguably supporting them.
Most of the human ghosts were this, such as Mikihisa in the future.
Matamune was one of the few ghosts and characters in general to be genuinely humble, very wise and witty. He displayed amazing powers against the Oni and soon disappeared into the spirit realm this was because his mana for existing on the material world was fading, and seemed to imply that because of his predicament, his powers were much lesser than 500 years ago. If Yoh had continued to use Matamune as his ally, it would've been much easier to go through the preliminaries.
Yoh is Hao's twin but we never get to see Yoh developing a power similar to Hao. In the manga, Hao says that he wants to consume Yoh's soul but we never get what will he win.
This is later rectified in the anime when he does manage to consume Yoh's soul and appears much stronger for it. Until Yoh frees himself and Hao's strength decreases accordingly.
The idea of stasis vs. change, first introduced early in the manga. Initially, when it was just a Slice of Life story, it was not uncommon to find shamans commenting about how humanity is always rushing around and changing too fast, while shamans seemed to value places still connected heavily to the past (which makes sense; their powers involve the remains of the past after all). If this idea of shamans clinging to the old ways and normal humans rushing into the new had been consistent throughout the manga, it would have made a far more interesting Grey and Gray Morality, as Shamans, though powerful, wouldn't like embracing technology, and humans, though weak, would be able to invoke Muggles Do It Better in many instances. After all, while Shamans are more 'one with the world' and have been such for centuries, there's a reason why it's only recently that overall health and human rights are on the upswing and starvation and plague are going down. But instead, shamans in the series seem to reject most technology due to their Green Aesop nature, except where it would allow Muggles the advantage, but still manage to ignore the good parts of human development which they themselves have adopted and constantly talk about humanity's downsides, forcing humanity as a whole into a story role of inferior uselessness while at the same time turning the shamans' perspective into utter hypocrisy.
Ugly Cute: Sure, Chocolove's appearance is a bit outdated and offensive to those who don't realize why such Values Dissonance is in place... But that doesn't stop a small handful of fans from finding him absolutely adorable.
What might help is that he coincidentally resembles another, more famous Ugly Cute character, Usopp.
Unintentionally Unsympathetic: Hao is supposed to be a Tragic Villain, and the audience is supposed to see his eventual ascension to Shaman King as a good thing. Unfortunately, the cold hard truth is that most of the cast have pretty tragic backstories too, to one degree or another, and none of them grew up to be genocidal monsters out to exterminate "baseline" humanity! Many readers instead regard him as a Karma Houdini of the highest order, and one who hasn't necessarily abandoned his plans for worldwide mass death and destruction so much as delayed them.
What doesn't help matters is that Hao's goals come as petty, arrogant, and hypocritical. He goes on big rants about how Humans Are the Real Monsters with them always fighting, killing each other or things that are different than them, and destroying the harmony of nature. The final nail in the coffin is that Hao is all of those things, and he's killed far more people than he cares to count (the body count is at least in the thousands). Many of his actions killed other humans or shamans alike; one of which that caused Lyserg's start of darkness. Compared to Hao who only lost a total of three people in his past lives: his mother, his first friend Ohachiyo (by his own fault due to revenge), and Matamune (who abandoned him when Hao went off the deep end). No wonder he comes off unlikable by a lot of readers. At least the anime adaption pointed out, in-and-out of universe, how wrong his philosophy and views were, and how they are most definitely not something you should sympathize with. The manga seems to try to do this, but fails spectacularly and seems to almost agree with Hao.
The Woobie: Each of the characters can be seen as this, especially Ren, Anna and Lyserg. Yoh seemed to not be this but Volumes 19 & 20 proved this very wrong, after losing his first spirit ally and friend outside of the household.
One of the good changes from both the anime and manga: renaming Chocolove to "Joco". The original name is both unwieldy and potentially offensive, while Joco sounds like an actual name as opposed to a racial slur.
In the Viz Media's manga edition, Chocolove's lips were also edited to match those of the rest of the cast as opposed to the large, thick ones he originally had. It pays to be racially sensitive and it was initially pretty offensive. In the anime, the lips remained, presumably because it's much hard to edit lots of animation frames than it is to edit still pages.
Most African-American characters or those with similar heritage received the same treatment throughout the manga.
Averted big time in the Mexican Spanish dub of the anime, and also in the Mexican Spanish manga translation. In fact, the Mexican Spanish dub of the anime makes Chocolove even more offensive (and funnier) by giving him a Southern accent (who is normally reserved in Mexican Spanish for hillbillies or Native Mexicans alike). There are times when Horohoro is racist to Chocolove in the Mexican dub but these lines are really short lived.
Also, in the English dub of the anime, Opacho was changed from a girl to a boy. Luckily, her/his gender isn't brought up much in the show, and she/he is still voiced by a woman.
Vocal/Larynx Dissonance: Those who are used to watching the Japanese version may feel this way about the English dub, where most of the younger males-originally voiced by women-are now voiced by guys. Especially the case for characters with higher-pitched Japanese voices, like Chocolove or Manta.