It is not a skirt. It is called a loincloth.
The belt is called a Mawashi and the apron like garb worn when entering the ring is a Kesho-mawashi
LOINCLOTH
breechcloth or loincloth
loincloth(s)
Olympic competitors are called Olympiads.
American Wrestling
cus it iz amatuer wrestling
Wrestling is done on mats.
A loincloth can also be called a lungi. This is commonly worn in India, Pakistan and Malaysia. A dhoti is shaped like a sheet whereas a lungi is more skirt like. It is preferred to trousers in humid climates.
competitors
a luger?