Our 6th grade is still in elementary school here. The group, or clique, shuffling started in the 4th grade. That was a bad year for my daughter, Carol. She is now in the 7th grade and, over all, it has been a good year. The 6th grade was hard. Some of her good friends stopped hanging around with her and she, to this day, doesn't know why. So she just drifted from group to group. She is finding her own way now but it hasn't been easy. Her old friends have begun talking to her again but she isn't included as part of their "group".
Carol talks to everyone and has made friends with some of the 8th graders. She doesn't belong to one particular "group" and has lots of friends. How this works out, time will tell.
My son, James, who is now in the 10th grade had a much easier time. Each year, since 6th grade, he has had one boy (not the same one) try to bully him. He has just turned it back on the boy and never had a problem after that. The boy always tried to verbally intimidate him and James never backed down and turned the bullying back on them. Usually the boy was putting James down in some way. So the bully just backed off.
Now he has had so called friends try to physically bully him and he doesn't back down there either. Since James is stronger than he looks, he just gave back what he got and they realized that they couldn't intimidate him. And these guys still call James their friends. Go figure?!
With James, it has always been intimidation, whether physical or verbal. He just lets them know that he won't be intimidated. At this point, nothing has led to an actual fight. Hopefully it will never lead to that either.