Most annoying MUGEN character you have ever fought?

[Octavia Melody]

Feather Dhaos has way too much hit points (which he also REGENERATES), and attacks that only a flying character could dodge.

[SSBKing65✯]

Many, including those overpowered DBZ characters, Floren & Hato Sabure, they will troll you at any time. Dark Storm K, Goodman, Rare Akuma, who ruined my 62 win streak in Survival. 

[ろくお 石田 (旗 の 心)]

All character of Googoo64. but i beat all without using cheap characters and I had to restart the round many times by many bugs in their characters.

[LuckyShigemori7]

Patchouli Knowledge, OMF, I CAN NEVER BEAT PATCHY ON MY OWN UNLESS REISEN IS MY PARTNER OR IF I HAVE ANOTHER PATCHOULI AS MY PARTNER. :P

[PlasmoidThunder]

I've developed a slight hatred towards Guilty Gear-esque characters with the infinite air juggles.

Once you're in the air, put yer controller down son 'cuz you're never getting dropped.

[Big Green]

While I can't deny how fantastic they are, Kamekaze's characters are a pain in the butt to fight. The number of times I've beaten them are in the single digits.

Also, Ronald McDonald.

[PlasmoidThunder]

I believe Kamekaze's characters are affected by MUGEN's difficulty setting. Perhaps you should set it to an easier difficulty?

[Big Green]

I believe Kamekaze's characters are affected by MUGEN's difficulty setting. Perhaps you should set it to an easier difficulty?

I use the default setting.

Yeah. I should probably git gud.

[A person]

2580shota's characters. ALL OF THEM. 

[Big Green]

I would have to say MVC2 Strider Hiryu by Hiryu. this guy has 3 different cmds for his difficulty settings. on hard he is almost unkillable(f1 is the only thing that can kill him but on rare ocasions he can "dodge" it) he has long combos, can block while stunned and if you somehow get his health low, whatever hit that would/could/should kill him is didged and he recovers 25% of his health. not even rare akumas instant kill raging demon can kill him. he backflips out of it like nothing. they fought for half an hour untill akuma cheated and used F1

Judging by the alternate .cmds and the author name, I think you're talking about Kong's version.

Many, including those overpowered DBZ characters,

Speaking of DBZ, Stig87's Ginyu, while a balanced character nonetheless, cut many of my survival runs short because his A.I always kept on spamming the "Pull you into the ground and smack you repeatedly" hyper once it got enough power. CHOUJIN's Piccolo is also a pain in the butt to fight. I've probably beaten Piccolo the least comapared to his other characters (who are pretty hard to fight against already).

[Reigizuo_78]

BLACK's new character Agni................OH. MY. GOD.

[Riku Minato]

for me my most annoying MUGEN character I have ever fought are: 

-Rikard's characters(with AI Patches)

-Orochi/Mizuchi characters