in my experience bullies are normally big and hard
I have to agree with that. The idea that if you hit one they'll run home and cry for their mummy is laughable.
At secondary school the bullies were all from the council estate, brought up on fighting, stealing and educationally a waste of space. I'm not sure what value there would be in telling your son to strike out. It's not something you can teach and could make the situation worse.