The following credits are all the staff responsible for creating FFXIII Versus.

FFXIII Versus Staff (PS3)

Director: Tetsuya Nomura (FFVII: Advent Children. KH, KHII)
Character Design: Tetsuya Nomura (FFVII, FVIII, FFX, FFX-2, KH, KHII)
Movie Director: Takeshi Nozue (KHII)
Composer: Yoko Shimomura (KH, KHII, Super Mario RPG, Street Fighter II)
Producer: Shinji Hashimoto (FF Series, KH Series)
Scenarist: Unknown, possibly Tetsuya Nomura and/or Kazushige Nojima (FFVII, FVIII, FFX, FFX-2,KH, KHII)

(By FFFreak)