Legwear

Shorts are a type of unlisted attire in Splatoon, and proper clothing items in Splatoon 2 worn by Inklings.

Splatoon
In Splatoon they are not changeable and always have the same appearance: black, with a stripe of the wearer's ink color on either side. They have no other role in the game whatsoever. The only gear that does not have the standard shorts are:

Splatoon 2
In Splatoon 2 pants are now proper clothing items and can be changed into different types, including longer pants and khakis.