The Blue, Green, Red, and Yellow Costumes are the four default colours of Marapets. Them and the Purple, Pink, White, Aqua, Coral, Brown, Black, Grey and Orange Costumes are amongst other Colour Costumes in the Costume Boutique.
The Blue Costume was temporarily retired despite being a default colour.
For some education, Red is at the end of the light spectrum, Yellow is the most visible color to the naked eye, and Black, White, Grey are monochromatic colours - meaning they lack support from other colours.