I'm going to be doing a Save My contest of all of the characters ever to be in a character battle. This includes Character Battles 1-8, Got Villains, Rivalry Rumble, and all official Bonus Matches. So I compiled what I believe to be a complete list of all of those characters and came up with 323. Here's the list, let me know if you see any missing before I start the contest. Quite an impressive lineup!
Abe
Ada Wong
Adolf Hitler
Aeris Gainsborough
Agent 47
Agent J
AiAi
Akira Yuki
Akuma
Albedo Pisaora
Albert Wesker
Altair
Alucard
Alyx Vance
Amaterasu
Amy Rose
Andross
Ansem
Arthas Menethil
Auron
Axel
Axel Steel
Aya Brea
Balthier Bunansa
Banjo
Bartz Klauser
Bidoof
Big Boss
Big Daddy
The Black Knight
Black Shadow
Blinky
Bomberman
The Boss
Bowser Koopa
Bub
Captain Falcon
Captain John Price
Captain MacMillan
Captain Olimar
Carl "C.J." Johnson
Carmen Sandiego
Catherine
CATS
CD-I Link
Cecil Harvey
Celes Chere
Charizard
Chell
Chop Chop Master Onion
Chris Redfield
Chun-Li
Cid Highwind
Claire Redfield
Claptrap
Cloud Strife
Commander Shapard
Conker
Cortana
Crash Bandicoot
Crazy Redd
Crono
Dan Hibiki
Dante
Darth Revan
Daxter
Deckard Cain
Delita Hyral
Diablo
Diddy Kong
Dirk the Daring
The Dog
Don Paolo
Donkey Kong
Dr. Albert Wily
Dr. Fetus
Dr. Ivo "Eggman" Robotnik
Dr. Nefarious
Dr. Neo Cortex
Dr. Wallace Breen
Dracula
Duke Nukem
Earthworm Jim
Eddie Riggs
Ellis
Ezio Auditore da Firenze
Falco Lombardi
Fawful
Fei Fong Wong
Felix
Fox McCloud
Frank West
Frog
Gabe Logan
Galcian
Ganondorf Dragmire
Geno
Ghaleon
Gilgamesh
Giygas
GlaDOS
Goemon
Golbez
Gordon Freeman
The Great Mighty Poo
Gruntilda
The Guy
Guybrush Threepwood
Haseo
Heavy
HK-47
Hogger
Ike
Illidan
Iori Yagami
Isaac
Ivy Valentine
Jade
Jade Curtiss
Jak
Janus "Magus" Zeal
Jay Solano
JC Denton
Jecht
Jill Valentine
Jim Raynor
Jin Kazama
Jinjo
Joanna Dark
Kaim Argonar
Kain
Kain Highwind
Kairi
Kane
Kasumi
Katherine
Kazuya Mishima
Kefka Palazzo
Ken Masters
The Kid
King Dedede
King K. Rool
The King of All Cosmos
Kirby
Kite
Knuckles the Echidna
KOS-MOS
Kratos
Kratos Aurion
Kuja
Ky Kiske
Kyo Kusanagi
L-Block
Laharl
Lara Croft
Lavos
LeChuck
Lenneth Valkyrie
Leon Scott Kennedy
Lightning Farron
Link
Liquid Snake
Little Mac
Lloyd Irving
Luca Blight
Lucario
Lucas
Luigi
Luke fon Fabre
M. Bison
Manny Calavera
Marcus Fenix
Mario
Marle
Marth
Master Chief
Master Hand
Matt
Max Payne
Meat Boy
Mega Man
Mega Man X
Meta Knight
Mewtwo
Mid-Boss
Midgar Zolom
Midna
Miles Edgeworth
Miles "Tails" Prower
Missingno.
Mithos Yggdrasill
Morrigan Aensland
Mother Brain
Mr. Driller
Mr. Resetti
Ms. Pac-Man
Mudkip
Nana
Nathan Drake
Nathan Hale
Neku Sakuraba
Nemesis
Nero
Ness
Nidoran F
Nightmare
Niko Bellic
Officer Frank Tenpenny
Orochi