Miss Power - Deadly Alliance
Stunning young blonde in a hot dress visits a gang with a plan on how to kill Miss Power. After showing she's the boss, she then leads Miss Power to their lair. Busty Miss Power shows her strength and power by beating them up, before then facing the blonde.
However there is more than meets the eye with the young girl and she herself transforms into a black-clad spandex super villainess and proceeds to beat Miss Power.