I had something extremely similar happen to me.
Everything was the same as you said minus the whole sports and new school.thingy, and instead of me being the one who stood up and knocked the bully snseless, it was a friend of mine whom had been telling me I could stand up for myself and beat the bully's ass. Then one day in class the bully (God, I hate this f*cking word, yo) started throwin' stuff at me like chewing up paper and shooting it tgrough a straw, and when we walked out of the classroom he started hitting me in the back of the head. My friend saw this and immediately grabbed the bully by the shoulder, turning him around to face him, just just knocked him out cold with one punch. He couldn't get up and then a bunch of people srronded hm to try and help and sh*t. Me and my friend just kept on walking and I was nervous as sh*t
We didn't get in trouble afterwards either cuz the school was full.of ghetto people and fights were quite common.
Your friend did a good job lol, a bully deserves that.