With one or two exceptions, Dragon Ball characters aren't complex at all. This should mean that, so long as they're well-conceived from the start, they shouldn't be difficult to write well. Unfortunately, Dragon Ball Super exists, and shows just how horribly the most iconic heroes and villains in anime history can be written. Dragon Ball Super frequently suffers from poor writing, and characters like Goku and Vegeta aren't spared the effects of this.
Time and time again, the anime undoes character development, egregiously mistreats its cast, and flat-out portrays characters in ways that cause them to not resemble themselves at all. Dragon Ball Super Super is also responsible for introducing a host of new characters, and some of them proved to be awful inclusions in the series, with no redeeming qualities.

Frost debuted with great potential, seemingly being a heroic counterpart to Frieza. Almost immediately, though, this turned out just to be a facade. In reality, .
The plot twist surrounding Frost does nothing for the Universe 6 Saga, apart from giving Vegeta the chance to beat someone who vaguely looks like Frieza. Frost himself lacks any substance, and he only gets worse when he returns for the Universe Survial Saga. His brand of smugness just comes off as annoying and, with how weak he's already proven to be, it's impossible to take him seriously as a threat.

Dragon Ball Super writes Goten the same way he's always been depicted, and that's not a good thing. In a series where even his best friend Trunks gets occasional storylines and bits of development, He's simply the same lovable idiot he's always been, and the anime's lack of interest in changing that couldn't be more clear.
Since the Buu Saga of Dragon Ball Z, Goten has felt like little more than an extension of Trunks, and this is an issue that still hasn't been addressed. Even with Trunks and Goten taking center stage together in the Super manga's High School Saga, Goten still got nothing to himself. It's sad that even Dragon Ball GT did a better job handling Goten's character than Dragon Ball Super Super has.
The deuteragonist of Dragon Ball Super, Vegeta is frequently one of the best-written characters in the series. His friendship with Goku, his modern relationship with Bulma and their kids, and his mentorship of Cabba are all gold. Unfortunately, . At the end of Dragon Ball Z, Vegeta was able to let go of his obsession with Goku, and accept that he was the superior fighter.

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Whereas Dragon Ball GT got some of its best material out of expanding on this, Dragon Ball Super ignores it completely. Vegeta is as obsessed with surpassing Goku, and with training in general, as ever, he constantly spouts off the same stock lines about Saiyan pride, and it's both boring and insulting. Equally boring and insulting is how repetitive his role in Super is. Despite being the second-most important character, Vegeta is still only around to lose fights and make Goku look better by comparison.

Dragon Ball Super's mishandling of Gohan is one of the most common critiques levied at the anime. But while criticism is definitely deserved, it isn't for the reasons most fans think. Many people hate Gohan in DBS simply because he spends most of it not wanting to be a fighter, but the actual issues lie within that very mindset. Gohan's biggest problems in Dragon Ball Super are that the anime can't decide what to do with him, and that it looks down on him for choosing the direction that makes the most sense for his character.
He repeatedly goes back and forth between wanting to commit to training, and wanting a peaceful life, and the series goes out of its way to make him seem pathetic whenever he chooses the latter; it's as if Vegeta is writing the scripts. , seeing as "Beast" is a contender for the most poorly executed transformation in the franchise.
The face of the franchise, . The series cranks his stupidity, selfishness, and obsession with fighting strong opponents up to eleven, and it often makes him insufferable. Some fans will argue that it isn't that bad, and is in line with how Son Goku has always behaved in the Japanese version of the franchise, but this just isn't true at all. In the past, Son Goku was never a superhero, but he was a pure-hearted individual who went out of his way to help others.
Goku also wasn't particularly dumb, rather just being naive, uneducated, and disinterested in learning about things he didn't need to know. Dragon Ball Super paints Goku as comically idiotic and mean-spirited, and this is worsened by the fact that the series rarely calls him out for this in any meaningful way. Additionally, because Goku completed his character arc all the way back in the Cell Saga, he has little narratively to ever actually contribute to Super's stories, often just feeling along for the ride in his own series.

By and large, fans absolutely adore Master Roshi's role in Dragon Ball Super, and it's easy to see why. After sitting on the sidelines for all of DBZ, Roshi gets to participate in fights, look cool, enjoy emotional moments and, in the manga, go toe-to-toe with Jiren. Like much of the series, Roshi's role in Super is fan-service, but the fans who get a kick out of this may need a reminder as to why the Turtle Hermit was ever on the sidelines in the first place.

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In the 22nd World Martial Arts Tournament and King Piccolo Sagas, Roshi retired from fighting due to his age, made his final stand against King Piccolo, and trusted the future of martial arts to Goku and Tien Shinhan. By randomly revealing that he's been doing secret training that makes him relative to the other Z-Warriors, all the narrative and thematic weight of two of the franchise's best arcs are undercut. This is without even mentioning how .

Videl's treatment in Dragon Ball Super is baffling. In an anime that goes out of its way to treat Bulma, Android 18, Chi-Chi, and Pan with more respect than they ever were previously, . There isn't a trace of the endearing personality she had in Dragon Ball Z, and she's reduced to simply being a kind and demure housewife and mother.
It would be one thing if Videl simply never had the chance to display her old personality, but several have indeed come and gone. She's become the most boring member of the Dragon Team, and arguably the most wasted. It's doubtful Videl will ever be relevant again, but Dragon Ball Super could at least give her back some of her old fire.

Jiren is the most iconic new antagonist in Dragon Ball Super, but that doesn't mean he's a well-written opponent for Goku. The strongest mortal in the multiverse, at the time of the Universe Survial Saga, Jiren serves as the wall that Goku needs to break through in order to win the Tournament of Power, and that's all there is to him. , and his actual personality is as bland as can be.
What makes Jiren's writing so egregious is that he's the main antagonist of the Universe Survival Saga. If Top was Universe 11's strongest warrior, and Jiren was just his intimidating and stoic right-hand man, there would be no issues with him. Under-developed henchmen are fairly common in the franchise, and it would be easier to appreciate his absolutely incredible fights if he were merely following the orders of his far more rich and interesting friend. But, as things stand, Jiren represents everything that a main villain in Dragon Ball shouldn't be.

As bad as the writing can get for certain characters throughout the franchise, it almost never feels like any actual malice is involved in their mistreatment. The sole exception to this is Tien Shinhan's character assassination in Dragon Ball Super. While Dragon Ball Z always tried to pay some respect to the former strongest man in the world,

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Throughout the Universe Survival Saga, Tien is portrayed as wholly incompetent, as he fails to teach his martial arts students ki control, loses a fight to Roshi, gets bullied by Gohan, and turns in a pitiful performance in the Tournament of Power. All the while, he's written with all the personality of a background character. Things don't get any better for him in the Galactic Patrol Prisoner Saga, in which he can't even come up with insults to combat a Metalman with, despite him having initially been introduced as the series' biggest trash-talker.
Bardock is the only character in Dragon Ball Super whose writing is so abysmal that it retroactively ruins the best arcs of Dragon Ball Z. Under no circumstances was the series required to stay loyal to the portrayal of Bardock in Bardock - The Father of Goku, as that special had no involvement from Akira Toriyama. However, it also wasn't required to not only canonize Dragon Ball Minus, but double down on it. Dragon Ball Super portrays Bardock as a loving father and a selfless hero who wasn't like all the other evil Saiyans. It does this not only during the worst part of Dragon Ball Super: Broly, but in an entire extended flashback in the Granolah the Survivor Saga.
By writing Bardock this way, , but one of him naturally being good because of who his parents were, and being destined to avenge his people by defeating Frieza. And, while it may not be fair to compare, Super's overtly heroic and nice Bardock just isn't as interesting a character as DBZ's, who was a monster that just so happened to be thrust into playing the part of an aspiring savior. This is all without even mentioning Bardock's retconned in wish on the Dragon Balls, which ranks as one of the most confusing narrative choices in the franchise, as it actively makes all of Goku's achievements throughout the years less impressive.