bullies generally are not getting their ass beaten at home enough or at all.
Spare the rod, spoil the child. i've had to spank my kid maybe 4 times in his 9 years. i stress to him when i drop him off at school to make friends, be nice, never to single anyone out. if i ever heard of him doing any of these things, i would be infuriated.
i don't want him to be a sissy, and he is in martial arts to learn how to protect himself. (he is small for his age, as i was) i try to keep up with his friends and ask him if there are any kids that are new or don't seem to fit in. if so, i tell him to make it a point to befriend that school.
always using the thought, "how would he feel if he were that kid, or if someone were picking on him"