Interesting indeed...
I'll try the Real McCoy...
Like the other original X-Men, the Beast was given a standard training uniform by Xavier. His version, however, included no boots or gloves, as they would hinder his ability to cling to or bounce off walls. [X-Men (1st series) #43 backstory]
Jean Grey later redesigned the training uniforms and, while hers changed into a more “female” version, the ones of the male X-Men more or less stayed the same. She only added a red belt and the yellow shirts were no longer covering the entire upper body. [X-Men (1st series) #27]