Here's an example: a small, simple, Street Fighter II-sized roster.

-Ichigo Kurosaki (Bleach)
-Ken the Eagle (Gatchaman)
-Sailor Moon (Sailor Moon)
-Kenshiro (Fist of the North Star)
-Rangiku Matsumoto (Bleach)
-Zoey Hanson (Mew Mew Power)
-Spike Spiegel (Cowboy Bebop)
-Vash the Stampede (Trigun)

Ok, here's my roster of Seinen Fighters. The theme is fighters from mature anime (no Shonen or Shojo).

Row 1: Alucard (Hellsing), D (Vampire Hunter D), Jubei (Ninja Scroll), Iria (Zeiram), Desert Punk (Desert Punk)
Row 2: Kenshiro (Fist of the North Star), Maki (Air Master), Afro (Afro Samurai), Priss (Bubblegum Crisis), Wild Tiger (Tiger and Bunny)
Row 3: Motoko (Ghost in the Shell), Armitage (Armitage III), Vash (Trigun), Birdy (Birdy the Mighty), Yomiko (Read or Die)

My ideal fighting game? This'll be fun!~
So basically, the game would take place in a giant metropolis, and each character has it's own respective area for fighting (say a penthouse, or an alley, maybe even a train station). And you have to work you way across the city to the final boss! xD

-Yuno Gasai (Mirai Nikki)
-Izaya Orihara (DuRaRaRa!!)
-Kyouko Sakura (Puella Magi Madoka Magica)
-Ryoko Asakura (Haruhi Suzumiya series)
-Maka Albarn (Soul Eater)
-Crona (Soul Eater)


;u; Can you tell I haven't really seen a lot of fighting anime?

Back when I was a member on Capcom Unity, one forum topic had us suggesting ideas for crossover games. One idea I had was Funimation Vs. Capcom, which, as the name obviously suggests, pitted Capcom characters against characters from anime dubbed by Funimation. I thought it was an awesome idea... until the people told me that it couldn't happen due to licensing issues and such. I still think it'd be a cool idea for a fighting game, though.

Funimation side
-Aya Iseshima (Master of Martial Hearts)
-Ganta (Deadman Wonderland)
-Moka Akashiya (Rosario + Vampire)
-Kurumu Kurono (Rosario + Vampire)
-Vash the Stampede (Trigun)
-Makina Hoshimura (Corpse Princess)
-Falis/Princess Alita (Murder Princess)
-Rin Asogi (RIN: Daughters of Mnemosyne)
-Musubi (Sekirei)
-Van (Gun X Sword)
-Maka Albarn and Soul Eater Evans (Soul Eater)
-Nadie (El Cazador de la Bruja)
-Yamada (B Gata H Kei)
-Casshern (Casshern Sins)

Capcom side
-Ryu (Street Fighter)
-Guile (Street Fighter II)
-Morrigan Aensland (Darkstalkers)
-Dan Hibiki (Street Fighter Alpha)
-Cody Travers (Final Fight)
-Chris Redfield (Resident Evil)
-Regina (Dino Crisis)
-Geo Stelar (Mega Man Star Force)
-Phoenix Wright (Ace Attorney)
-Frank West (Dead Rising)
-Jin Saotome (Cyberbots: Full Metal Madness)
-Dante (Devil May Cry)
-Hayato Kanzaki (Star Gladiator)
-Linn Kurosawa (Alien Vs. Predator)
-Vanessa Z. Schneider (P.N.03)

Here's a roster of lady fighters from "less serious" anime than the other roster.