Real rain pours

The evil Ginga Sentai Gingaman make their first appearance from Episode 9 of Chikyu Sentai Fiveman “Gingaman Appear” (登場ギンガマン). They were part of an evil plot to first make the people of Japan believe that not all aliens were a threat and then lure them into filming a battle between the Gingaman team and the monster of the week, who would then use his powers of hypnosis to mind control everyone watching into loving Empress Medō.

They were eventually exposed and defeated but lived to return again much later in the series. The entire team is composed of male aliens from various worlds conquered by Galactic Imperial Army Zone including the planets; Baikan (Red), Monome (Blue), Grachis (Black),  Fujimin (Pink) and Gringa (Yellow). 

Though a team of villains that call themselves a Sentai, they don’t really transform so they don’t count as the actual first evil Sentai Team*. That honor still goes to Jaden Sentai NejiRanger.