Ou Hao often wore sweatpants to create a casual and fashionable style. His sweatpants were paired with jeans, plaid shirts, aviator jackets, and other different items, showing different trends. He also chose a loose-fitting style to make the overall appearance more comfortable. In addition, Ou Hao also liked to wear canvas shoes or yellow boots to show a sunny and handsome image. In general, Ou Hao's sweatpants gave people a youthful feeling, suitable for young boys to refer to.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
It's hard to pinpoint exactly where Gojo is at any given time in the manga. His whereabouts change as the story progresses and different scenarios unfold. It could be in a supernatural realm, a mission site, or interacting with other characters.