The Smurfette Principle: Dark Light is the only female in the main five.
Color-Coded: Dark Light wears black armor, Ray Trace wears orange-yellow-brown armor, Bluminesence wears blue armor, Ultra Viloet wears purple armor, and Kontrast wears white armor.
Palette Swap: The Protectors are all differently colored Baby Luigis.
The Leader - Dark Light
The Leader's Assistant, combination of heart and leader - Redshift
The Lancer - Ultra Violet
The Heart - Bluminescence
The Comic Relief - Ray Trace
The Muscle - Kontrast
I wouldn't classify them as a palette swap though, since they wear different outfits and have distinct physical styles to them.
The Leader - Grayscale
The Lancer - Phongik
The Big Guy - Cerulambert
The Smart Guy - Discharge
The Chick - Green Flash
The Coward - Crepuscular Beam
The Ladies man - Scatter