A lot of body builders I have worked with wear athletic tights and shorts.

For deadlifts I prefer people to wear warm-ups. Example would be you basic nike/adidas basketball/soccer style warm-ups. These have a little sheen to then and the bar glides up the leg better. Athletic tights are great too. I can't convince kids to buy/wear these though so I usually don't bring it up. Tradition sweatpants kind of get stuck on your legs when you sweat. I have seen these cause problems "riding up" during deadlifts.

For cleans... I prefer shorter shorts and a tight shirt. If the shorts are too baggy/long the bar sometimes catches. It isn't the friction (maybe it is to some) that bugs me but it is the distraction. Warm-ups work well here too. Tight-shirt would be like and underarmor type shirt. The bar should slide up your chest so give it something to slide on.

For squats... Loose shorts (tights if you will wear them is fine). Don't want your motion adjusting to your clothing at all. Also you don't want to deal with a split down the middle of your ass. You can wear warmups squatting but they would have to be loose fitting.

For bench... tight shirt. Underarmor style would work here. Some people wear bench shirts. I feel a tight shirt promotes rigidity and form.

For chin-ups and all the smaller movements... Doesn't matter.

A lot of body builders I have worked with wear athletic tights and shorts.

For deadlifts I prefer people to wear warm-ups. Example would be you basic nike/adidas basketball/soccer style warm-ups. These have a little sheen to them and the bar glides up the leg better. Athletic tights are great too. I can't convince kids to buy/wear these though so I usually don't bring it up. Tradition sweatpants kind of get stuck on your legs when you sweat. I have seen these cause problems "riding up" during deadlifts.

For cleans... I prefer shorter shorts and a tight shirt. If the shorts are too baggy/long the bar sometimes catches. It isn't the friction (maybe it is to some) that bugs me but it is the distraction. Warm-ups work well here too. Tight-shirt would be like an underarmor type shirt. The bar should slide up your chest so give it something to slide on.

For squats... Loose shorts (tights if you will wear them is fine). Don't want your motion adjusting to your clothing at all. Also you don't want to deal with a split down the middle of your ass. You can wear warmups squatting but they would have to be loose fitting.

For bench... tight shirt. Underarmor style would work here. Some people wear bench shirts. I feel a tight shirt promotes rigidity and form.

For chin-ups and all the smaller movements... Doesn't matter.