For proof that Bulma is (or was intended to be?) an actual character in “Budokai 3” in some capacity, look no further than the “exclusive bonus DVD” that came with the Collector’s Edition of the game. During some of the behind-the-scenes shots of actual voice work being performed on the game if Tiffany Vollmer, FUNimation’s voice actress for Bulma, actually performing typical “Yah! Hiya! Ha! Ooyah! Get back! Ha!” fighting sounds.
In somewhat related news, Jeremy Dunham of IGN has reviewed the game and gave it a flat 8.0.