Guys like Ninja Red, Mega Red, Time Red, and Geki Red may not be the leaders of their respective teams. But their suits were designed for the leader. Being the leader of the team and being the guy who gets to wear the leader suit are two different things.
The order of the suits for the Kakuranger team was supposed to be red, white, yellow, blue, and black. Yet it's the one in the white suit who got to be the leader. The Megaranger team has the suit order being red, black, blue, yellow, and pink yet black is the leader. Timeranger was the same as Megaranger with a black being swapped for green. Yet ironically pink (who's number is 5) is the leader.