If he doesn't care, maybe he just isn't a good friend. No matter what you do, he won't change I'm afraid, people don't change willingly or even if you summon something to scare him to change. He won't that's who he is.
It sounds like he is being immature, if that's the case, you could tell him to grow up. I do agree on recording him, showing a teacher or your parents, if he's bullying you and others. If you don't want to that, then I am not sure what you can do.
I wish you luck. Becareful when summoning entites, spirits, demons, etc, they could hurt you, instead of him, be wise when you are summoning, and make sure to protect yourself.