Research and representation aside, I actually find liking a lot of Sonic fights.
Vegeta vs Shadow was fun for S1, MvS1 is more in character than MvS2, Eggman vs Wily was fun, I'm one of the sickos who likes most of Luigi vs Tails' fight and even DK vs Knux was really funny, Flash vs Sonic has banger OST and Shadow vs Ryuko was good since I didnt watch KLK so I cant get pissed at bad characterization of Ryuko.
Amy vs Ramona & Metal vs Zero were kinda ehh but only Shadow vs M2 was truly bad and MvS2 had the worst characterization, but majority of Sonic fights have been good.
Ignoring that with current stats Sonic is the most robbed series and they get the weirdest "canon" sources used lmao
The only ones I personally find myself liking much are Shadow v Ryuko (though I will admit Ryuko's characterization was poorly handled. While not a character assassination, it just uses the wrong Ryuko as the wrong time, also kind of poor sound design), and I give MvS1 & Eggman v Wily a pass for their age, as despite that I find them fun fights overall.
Vegeta v Shadow you really don't get much out of if you don't like TFS, and I don't have any attachment to them, Luigi v Tails and Amy v Ramona are boring filler fights in which the former has Luigi get stomped with little recourse and the latter just being slow and boring in a
Sonic Franchise Fight, Knuckles v DK I don't like because Knuckles' characterization is actively unbearable and holy shit that DK sprite is ******* hideous, and I think the research/compositing actively hurt the fight, Metal v Zero actively sucks ******* ass and is a terribly animated fight with the worst sound design on the show and ugly ass pixelated 3D model cut-ins that constantly interrupt the fight itself.
MvS2 is my 2nd least favorite DB for reasons I've talked about before. I could write an essay for all the reasons I dislike that fight but wont unless any of you WANT to see that lol. In short though I think it's a terrible, ugly looking fight with poor character representation on both ends and some of the worst research I've seen for a Sonic episode.
Shadow v Mewtwo is the definitive worst episode on the show imo for reasons all of you probably know. Unfinished spite animation that was made to shit on one of the characters, nothing much to go over there.
Flash v Sonic isn't
terrible, but it's my personal most disappointing DB and one of my least favorites because I just have a lot of personal gripes with the fight that make me not like it. Ranging from disagreeing with the outcome and thinking it has one of the worst conclusions in DB (the finale of the fight barely makes sense on several levels, and the analysis conclusion itself ******* sucks), and I think the fight severely missed out on essentially all of its potential, barely had them banter, Sonic went out of character at the end, and most of their abilities went not utilized, it's the most disappointing DB for me because that's my personally favorite VS MU of all time.
I think Sonic has had horrible luck and horrible treatment on this show and it's why I'm often negative on Sonic episodes in general.