SO hard. Bullies exist after school too don't they? I think we have to get used to them. I think we possibly begin to learn how to live with them in our lives at school.
You can't try to 'get even'. You'll lose! So the only other option is to learn that bullies have to win. You let them. You suggest the child gets on with people he/she like, doing things they like. If the bully gets into this, then it just hurts. When it hurts, it hurts but it doesn't kill.
Just let them go on being bullies, let them wear themselves out. No response. But especially no self-righteous response!
It seems such useless advice, but thinking back on being a child and on life I realize one never wins against a bully, until 'something' happens to 'even things out' when there is some sort of justice (at some point).
I think life is about living with who we have around us, in situations we find ourselves in, and getting on with what we are supposed to be doing. The rest isn't up to us is it?