First and foremost you should be talking to her teacher. It is never be tolerated that there is meaness amongst classmates. Even if they cannot micro manage the class, it is to be presented as a whole that bullying, mean behavior and even clicks should not be allowed during school.
In the three years my daughter has gone to school the teachers have been very proactive not to tolerate and to work with the kids on this subject. In sixth it will get harder.
I can recommend if there are not a ton of girls in her class, to have a "party" for no reason. Invite the girls in her class to come over, hang out, order pizza and maybe come in jammies, have some games and promote outside of school activities. Kids have a narrow scope and go along with the crowd when I feel if they knew each other better outside of school they may realize they have more in common with each other and not to judge.
It is common and moving will not allow her to exert herself nor will it solve the problem. Moving will only teach her to run from her problems. This is such a common thing everywhere, there are even "clubs' at recess and my daughter is in second grade. I told her this piece of advice, "be with people that make you feel good about who you are, never judge someone else, never prevent anyone else to join you in your play at recess and always be the bigger person, if someone is mean, walk away and think maybe they are having a really bad day"
Friendships come and go and then there are the select few friends that can last a lifetime. I still am friends with my best friend from 3rd grade.
It takes effort, patience and promoting her self confidence. Friends don't define us, however they are a bonus in life.
If there is fighting within her class or someone is being abusive you need to address it with the teacher and principal. They have onsite couselors in most schools to help with this. Doing training work with the kids to help them be more empathetic to others and know what is appropriate.
Encourage your daughter to stand up for herself, but with dimplomacy, get her involved in other activities outside of school that she is good at to boost her self esteem and broaden her friendship possiblities. Work with the school, maybe set up outside of school get togethers with girls she may or may not associate currently at school with. Good luck, her self esteem is what you need to concentrate on as that will help her in all sorts of situations, now is just the tip of the crazy behavior and clickiness, it gets worse in middle school! If she stands proud and doesn't let people label or define her she will be okay! :)