I don't have kids yet but I was bullied in grades 7-8 (98-99) when I moved to a new town. My parents never condoned violence but they did not want me to be a punching bag and hated that I was getting bullied. I am not sure if it is the "right" way to help, but my father basically said "stand up for yourself, if you get suspended, I'll take you out to lunch". I think that was the green light... Anyways, kind of randomly in 8th grade art class (a frequent bullying time for me and one of my friends), I wound up and threw a huge punch at the lead bully's nose and completely connected. He never saw it coming either, it was when he was looking down at something. It knocked him out and broke his nose. Who cares if it was dirty, it showed him that I was not a benign punching bag and probably even more dangerously to his bullying mindset: I wasn't predictable anymore. We both got suspended and my parents weren't happy but they were proud that I stood up for myself. It felt really good to ruin that shitbags day, that's for sure. After that his whole group kept their distance and never physically bullied me. There were some verbal instances but it was laughable. I will probably offer the same advice to any children I have as it seemed to work out well for me.
It is weird though, out of that group, one is in jail or dead, another is a townie with a beer gut and is balding (we're 27), I almost laugh when I see him, and the others I lost track of. But I still remember the feeling and would probably not give any of them the time of day still.