Bitch-chan is an asshole, but I can get behind it. She's a spoiled rotten brat who will learn a lesson about humility and how a good personality is worth more than your appearance from an outcast girl. It's a tried-and-true tale and I'm sure it'll work just fine here. (Though the fact that it will end with the brat and outcast getting together is a plus.)
She does not seem to be THAT bad. Biggest issue is that all her friends and probably most of the school are constantly praising her. If you grow up in such an environment it is no surprise she turns out to be like that.
Also, that are just very common tropes for manga and anime. We have seen them in yuri manga many times and probably a lot more many times in all other kinds of genres.