They don't wear under uniforms but some wear white or team color sweatshirts or a nylon-type of long sleeves.
Baseball uniforms are used for the sport of baseball and football uniforms are used for the sport of football. Football uniforms offer more protection from injuries since it is more of a contact sport. Baseball players wear hats for the most part rather than helmets like football players wear.
American football players wear many things under their uniform. These include shoulder pads and thigh pads. If you are talking international football (soccer) then the main piece of equipment players wear under their uniforms are shin guards.
They wear a cup and protective pads
Yes, underwear to protect the under area
All of the MLB players currently wear Majestic uniforms.
what uniforms did netball players wear in the early 1900's
They wear under armor.
They wear majestic uniforms on the field
No tennis doesn't have uniforms. It is not a team game, but individual players. Players often wear a particular style of dress.