Hmm... a perfect Mugen?
Chars:
Violent Ryu (PotS/marancv)
Shin Akuma (PotS)
Ken (Warusaki3 w/no bars)
Spider-man (Seth Zankuten)
Insane Hiryu (SyN)
Ghost Rider (Wucash)
Tetsu (XCB)
Super Mario (ShinRyoga & NeOaNkH)
Sandman (McCready & Loganir)
Dragon Claw [boss] (Reu)
... that seems balanced enough.
Stages/music:
SF3 Basketball Court (T.I. - What You Know)
MkvsSF3 Attic (Hall of Fate)
ExodusTrain (the song it came with)
Freight Express (Bone Thugs - Flow Motion)
Gouken's Temple At Night (GZA - 4th Chamber)
KOF2000 Desert Stage (Xzibit - Concentrate)
Midnight Requiem (NaS - Hate Me Now)
Midnight Storm (music it came with)
Meteor Storm by SyN (Law's T3 theme)
New York Marvel (music it came with)
NGBF Secret Forest 2 (T5 Garden of the Tiger)
Samurai Champloo by DJVAN (PS2 Shinobi "Fate")
Suzaku Shrine Rooftop - Snow (Remix of Sonic 3's Ice Cap Zone)
SyN's Black Sonata (Crazy Train Techno)
TempleRMX by Me (King of Fighters 2000 ReBirth OC ReMix)
Life Bars = Fr33dom's Crystal Bars... a complete version