i didn't want to go too much into detail about dynamics but i thought it's necessary to specify some here
stan - bisexual, male pref (bottom > sub top)
kyle - bisexual, female pref (top > power bottom)
eric - queer/unlabelled (bottom)
kenny - queer, poly (switch)
tolkien - bisexual, female pref (top)
wendy - bisexual, male pref (top > power bottom)
tweek - unlabelled (top)
craig - gay (bottom)
butters - unlabelled , female pref, poly (top)
heidi - bisexual, male pref (bottom)
nichole - straight (power bottom)
bebe - heteroflexible (power bottom)
clyde - straight (sub top)
jimmy - bisexual, poly (top)
also - these are my general headcanons, but i can change up things (usually sexualities) based on what scenarios i want to explore