OP: 13:57, I understand. I want to know if it's totally out of line to ask.
dd is a rule follower and she's tasked by one of the teachers to report any fights/misbehaviours caused by this child. dd is happy to do this for the teacher but I have told her not to.
I know it seems crazy to tell dd not to do what the teacher says, but I just don't like this dynamics. I know she will be retaliated by this kid if she tattletales.
13:57 again. No, it's never out of line to ask. I just don't want you to get your hopes up. It's likely, with the situation you describe, many parents have made or will make such a request. Creating the class list from year to year is a crazy puzzle like process to balance, and some jurisdictions (like the district I used to work in) routinely turn down requests unless circumstances were extreme between two students. That said, ask anyway. As PPs have mentioned, focus on the issue of your child's experience. Also, be sure to mention your child has been asked to "report" on this other child, and how that contributes to your concerns. That is incredibly unprofessional of the teacher to ask her to do that. At the very least, even if they can't accommodate your request, at least they can address that issue.
Good luck.