Anime reached a peak in the 1990s and early 2000s that seems extremely difficult to surpass, even for reboots of these series that can't seem to hold a candle to their originals. Effort aside, there are even cases where a reboot has done more damage than simply continuing the franchise.
There are six for that reboots of classic series that ended up totally destroying the franchise. With poor animations and even worse sound and character design, the series caused much controversy among its veteran fans.

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Digimon Adventure 02 (2000)
They tried to innovate and completely screwed up
After 54 incredible episodes Digimon Adventure ended and the story of the eight chosen children and their Digimon Partners was concluded with a golden brooch. And in 2000, a reboot was released with a new set of chosen children and two from the previous cast. The story was marked as blandalthough the new 'Armor Evolutions' carry some weight in their own right (and are basically the only interesting thing in the series).
Later, the introduction of Jogress Digi Evolution also pumped it up a bit, but the pacing was absurdly slow and boring, and the filler episodes were so bad that fans thought this was the end of the franchise. Luckily, they got the awesome Digimon Tamers a few years later, which basically brought the sinking franchise back to earth after that absurd fiasco. Perhaps the only salvation in all this mess was Black War Greymonone of the best Digimon characters the series will ever have.
Shaman King
It was a good idea, but the pace was too rushed
Shaman King was and is one of the best anime of all time, even if it had its flaws (unlike other perfect Shonen like All Metal Alchemist). And when a 2021 reboot was announced, fans were ecstatic. But trying to cover all the manga volumes in just a few episodes was the biggest mistake they could have made.
Rushing through completely ruined itand the animations, designs, and other aspects of the nostalgic 2001 series were completely wiped. In the end, the cure was worse than the disease and Shaman King was buried under the weight of rushed development.
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Sorcerous Stabber Orphen
Look what they did to my poor boy!
AND horrible, poorly animated and frankly a total disaster of a reboot. It lacks the charisma, character-driven storytelling, and incredible soundtracks of the original version. Next to a horrible version of the Manhwa, Sorcerous Stabber Orphen received an anime reboot.
Sorcerous Stabber OrphenReboot 's is just a sequence of battle scenes ridiculously bad creature designs (especially Blood August, which acts like a green wyvern instead of a monstrous dragon). Pace again, character voices, animation: Everything is a total messand trying to put two and two together while watching is a complete waste of time. They really ruined it.
Knights of The Zodiac
An aberration of nature, it should never have seen the light of day
No real fan Saint Seiya he could take one look at it and avoid being disgusted. The very essence of what made Kurumada's work one of the most iconic and greatest shonen series is absolutely missing from this production. Not surprisingly, the fan score for this CGI animation was brutally low.
The voice acting is as bad as it gets, and even if they considered the original actors for this piece, it's not sure that would improve it. The facial expressions are stiff and clumsy, so much so that we could venture to call this series a “Mass Effect: Andromeda” modern anime.

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Rurouni Kenshin (2023)
A decent attempt, but absolutely lacking in comparison to the original
Rurouni Kenshin (Also known as Samurai-X) is one of the most famous shonen series in anime history. Created by the controversial Nobuhiro Watsuki, this anime saw a lot of action and changed hands on more than one occasion before finally being picked up by Liden Films (also in charge of the hated Berserks reboot).
At this point, Kenshin fans might start to believe that the series is cursed, as this reboot has done nothing but reignite the flames of rage among its die-hard fans, who believe that despite the colorful scenery and improved quality, the fight scenes and character designs are completely flawed and lifeless. The pacing is an absolute nightmare and the lack of original soundtracks hurts it in a very deep and personal way. To add insult to injury, a toned down Kenshin lacks magic in more ways than one, turning the memory of the legendary and charismatic ronin into a sad joke.
Berserk 2016
“Worst Reboots Ever” Winner: By a wide margin
WITH animation stiff as a statueand even worse use of camera than v Room film, Crazy The 2016 reboot can't even compare to the original from 1997. Considered by fans and pundits to be one of the worst reboots of all time, the series was the final nail in the coffin of an already dying franchise.
For reasons we cannot fathom, some even thought it did some good (even though it was bad), and that is putting Crazy again on the lips of fans and rekindled the audience's interest in this classic. Be that as it may, nothing good has come of it since then. Although the manga series (sort of) continued after the death of Kentaro Miura (by none other than his close friend Kouji Mori), it was more due to the audience's interest in the manga than the anime itself. After this fiasco, there is little chance for Berserk to get a solid animation. But we will always have the originalso there's a silver lining.

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