I am not savvy enough to comment on some of those, but there are a few characters on your list that don’t fit the description. For example, Xiaoyu actually got buffed in Tekken Tag Tournament 2 with some new tools and better properties on existing moves. Despite the removed JF laser scraper, which few could use, T5 Jin gained mobility, a dodging stance, and distance closing karate chops into kick making him roughly upper mid. T4 Lei was not a complete departure from TTT1 Lei (maybe weak in comparison to Jin, Heihachi, Steve, Nina, and Paul).
The biggest nerfs as far as I am aware:
Sean: Street Fighter III: Second Impact -> Street Fighter III: Third Strike
Lei-Fei: Virtua Fighter 5 -> Virtua Fighter 5: Final Shodown
Ukyo: Samurai Shodown II -> Samurai Shodown III
*All of the aforementioned went from best of the top tier to the lowest of the bottom tier.
Even the just frame laser scraper had match-up weaknesses against Christie/Eddy, Lei, and Kuma. It was overpowered, but saying that the entire game boiled down to it is a gross oversimplification. He was very good in 5.0 regardless with good punishes and more consistent damage output across his moveset. He was just outclassed by a number of broken characters, but could do well against all others. His complete toolset did not get hit enough across the board to make him go from best to worst.
Still haven’t seen anything that surpasses 3S Sean. He went from one of the best characters in Second Impact to a walking 2-8 or 3-7 match up. Capcom has admitted to purposely making him terrible. The only reason to pick him was to embarrass your opponent by winning.
SFV Season 1 Chun-Li, Ryu, and Nash to Season 2 of those three characters. All Season 1 top tiers that got put in wheelchairs for Season 2. And in Season 3 only Chun-Li has somewhat recovered.
SamSho2 Ukyo went from being a WTF broken character in 2 to being reasonable in 3. He’s good in just about every game (although I think 6 might be an exception.) Still, I’m glad to not have to deal with this kind of bullshittery in other games, so that was a Nerf I was happy with even though I mained him in SS1.
I also think TTT2 -> T7 Lars is worth mentioning; he did go from top 3 in the first to bottom 3 in the latter. However, he’s still quite playable, as with every T7-character. He’s outclassed rather than obsolete, so even though his relative placing as a character is drastically lowered, he’s nowhere near the other characters mentioned here.
Ukyo’s default Slash version in Samurai Shodown III is trash tier, even if his Bust version is closer to the middle. It is one of the many reasons that Samurai Shodown III is garbage in comparison to the rest of the SNK entries.
P.S. The only thing that Tekken 7 did right was showing that no one played Bob for the character or the play style.
3S Chun to SFIV Chun - while nowhere near as bad as 2I Sean to 3S Sean, it’s still a testament to how good 3S Chun was.
SFIV Gen to SSFIV/AE/USFIV Gen - SFIV Gen is one of those weird cases where people didn’t know how good he was during the time the game was being played competitively. In hindsight however, all the nerfs Capcom did to him were actually necessary - had they not happened (or had we stuck to vanilla SFIV), he’d end up running the game.
Ryo kof98 butchered in kof99. Since then He was never the same.
Yashiro, Yamazaki, Terry, Mary kof97 - kof98.
Chris, Daimon, Iori kof98 all suffered nerfs but nerfs done well in kof2002. Mature, Ralf, Clark, and Mary, however, got nerfed for no reason.