Pinky Roader and her two bodyguards is based off the pirate gal and her two henchmen from Secret of Blue Water I'm certain.

...granted I'm constantly certain that "Smash Daisaku" or whatever his actual name is, is based on M Bison as well.

...pretty sure Gunstar Green is Tetsuo from Akira as well.

...honestly Gunstar Heroes' characters largely seemed to be based off other media like goddamn the general dude who runs it all is basically fuggin Magneto and Char Aznable mashed into one.