Smoke Choked

One of many parody characters of Rozen Maiden in Nijikaku. This doll maid is a drunkard, always carrying a wine bottle with her and doesn't wear any pants or panties as a result. Her main gimmick is fighting with her giant wine bottle, smacking the opponent with it, tossing it at the opponent, and even taking a swig of it to get herself to vomit. This version of the character is censored.
By the Nijikaku team, edited by SSBKing 65
 

This Mickey is a mix of the various other Mickeys, like A.T.'s Mickey and DDR's Mickey, but he is primarily based on the Epic Mickey games.
By Crowsar
 

After Felix the Cat fell out of his prime, and before Looney Tunes hit it bigtime, Fleischer Studios was the greatest rival to Walt Disney. While Fleischer is more well known for Betty Boop and Popeye, Bimbo was one of the first of their characters and was conceived as a rival to Mickey. Hell, Fleischer had such a rivalry with Disney that in one of Bimbo's most iconic shorts, "Bimbo's Initiation", it begins with Bimbo falling into a manhole that then gets locked up by Mickey himself! In short, Bimbo was the original, most mischievous foil to the seemingly squeaky clean Mickey, but he didn't last as long as his contemporaries from the same company.
By Crowsar
 

Back in the 30s, Mickey Mouse was the hottest cartoon character on the market, even more so than he is today. Warner Bros. decided that they needed a character to directly compete with him...but what they created was a full-on knockoff of Mickey Mouse, named Foxy.
By Crowsar
 

Bosko, the Talk-Ink Kid was the first ever Looney Tunes/Merrie Melodies character, debuting back in 1929 in an unaired pilot short, and in 1930 in "Sinkin' In the Bathtub", which marked two of the earliest cartoons to feature soundtrack-synchronized speech and dancing. While he may have been the earliest Looney Tune, made during a time before Warner Bros. found their footing with Looney Tunes, and a character that led to innovation in the animation industry, I wouldn't consider Bosko to be a great character on his own merit. When it comes to his design, he was conceived in 1927 as a "negro boy" and maintained blackface stereotypes for a good while, even though Rudolf Ising denied that he was ever meant to be this. Hell, when Bosko's creators went over to MGM, Bosko went right back to being blackface to an even more obvious extent... Besides, most of his cartoons, with a few exceptions, were far off from the more anti-Disney style they'd go with once they entered the mid-30s with Porky Pig. But hey, that's just my opinion.
In M.U.G.E.N., Bosko plays similar to other creators by the same author.
By Crowsar
 

A cheap edit of Seplunker Sensei.
He has a Shoryuken that can send him really high, a Tatsumaki Sepukya that does more hits, altered stats and palettes, AND a OHKO Shun Goku Satsu.
By The Idiot Mugen Creator(Shazam123)
 

Believe it or not, there is a spriteswap in Nijikaku. This penguin mech is a spriteswap of Spelunker Sensei. I don't get why there'd even be a spriteswap in Nijikaku, considering that most of the characters were made from the ground up.
By the Nijikaku team

This is just Spelunker, but now his only hyper clones himself.
By the Nijikaku team

This version of Spelunker is a shotoklone, but does not have the lives mechanic. It plays just like a regular fighter, as if Spelunker had the Satsui no Hado.
By the Nijikaku team
 

So yeah, there are multiple Scotts in M.U.G.E.N.
By Ultra Fatality
 

The Aircraft Carrier Princess, and seemingly the only available creation of this author
By admiral

Asuta-san, or Astaroth, is one of, if not the most iconic character from Shinra Bansho. She is a high-ranking demon in the Imperial Demon Clan, ruling over other demons and leading them in invasion of the surface world. She is a character that spawned from a series of trading cards that came with Japanese chocolate wafers, which themselves spawned anime promo videos and a long-running browser game.
In Nijikaku, Astaroth's depiction is based on a 2ch meme that depicted her wearing goofy t-shirts, as she wears here. The meme version of her also hangs out with Spider-Man, for some reason. Her fighting style is very unorthodox, for instead of fighting herself, nearly all of her attacks are based around her using an apartment building and its residents to attack with.
By the Nijikaku team
 

An edit of Takakazu Abe that removes any and all of the yaoi elements from his character, replacing them with some more comedic stuff.
By ThisClown17

I don't know why, but Leo told me to download this character.  It's pretty decent, though.
By Frickin Username or mashu11
https://youtu.be/8hyFy1mOUFI

Another loli idol
By cwn

One of the only idols in Idolm@ster to be a loli.
A cheap, A.I.-only character. To disable her A.I., go to config.cns and change var(59)=10 to 0
By migo
 

のワの
Nonowa-san is a meme based on Haruka of Idolm@ster and her thinking expression. She was created by an anonymous artist on /ogame/ (live for online games) on 2channel (not to be confused with 2chan/Futaba Channel) back in 2007, and led to a lot of art pieces made of the character. She even got a chance to cameo in THE iDOLM@STER Dearly Stars: Neue Green, as well as in the 2011 Idolm@ster anime.
This character, as a result, is rather zany. She is a PlayStation era 3D model with plenty of crazy and trollish attacks, including an attack from referencing Takakazu Abe. Don't ask.
By w,h
2nd file: A.I. patch by SorekkiriP (stronger)
 

Referred to as the "Pretty-boy Idol" and prince of 765, Makoto Kikuchi is a tomboy.
I saw that the D4 version of this character was uploaded already, so I decided to upload the original.
By fu-lin
 

This thing seems to be some sort of mech, piloted by Chihaya Kisaragi? I can't seem to find anything about it online, outside of some image sources here and there.
By Haloveli
 

The mascot girl of Idolm@ster. Easily one of, if not the best Idolm@ster character made for M.U.G.E.N.
By ハロヴェリ(HaloVeli)
 

The character you play as in the Idolm@ster franchise. You are a producer of a group of j-pop idols, helping to lad them to stardom under 765. He has a "P" for a head in his M.U.G.E.N. depiction, due to how he is a blank slate character who we are to control.
By ハロヴェリ(HaloVeli)
2nd file: Helper file (I'm not sure what it does)
 
 

The original OS-tan, ME-tan is a fickle, clumsy, troublesome girl that uses onions to defend herself. She is based on the Windows ME, one of Microsoft's most infamous failures with its instabilities and frequent system crashes. She was created by MEあき on the /b/ (Nijijura) board of 2chan, not to be confused with the /b/ (Random) board on 4chan.
This version of ME-tan is done in a custom style
By Camren Springer
 

A parody of Rin Shibuya from The Idolm@ster that abuses Mio Honda...a lot.
By the Nijikaku team
 

The protagonist of the critically acclaimed Hollow Knight.  A simple 3 button character, with a fourth button for an extra move.
By Zobbes
 

Some guy in a barrel from a Taito RPG called Graffiti Kingdom.
By man