Monday- a. Red shirt, blue pants, white accesories b. Blue shirt, white pants, red assesories c. switch around a. and b.
Tuesday- (Not sure what you were like as a kid) but things I would suggest would be maybe be a tutu (if female), ruffles on shirts, Colorful shirts with lettering, colorful leggings, candy bracelets/ necklaces maybe?
Wednesday- (Don't know what decade day means) Maybe like oversized t-shirts/ hoodies, pastel, etc. probably anything to do with the 21st century
Thurday- Team t-shirts (if you have those), Black pants/shirt with red pants/shirt, you could put face paint with red and black under your eyes, Black and red tutus (sorry for so many tutu ideas) etc. etc.
Friday- If you don't like dresses than i'm guessing it means church clothes so try that domain maybe?