There isn't anything you could have done. <wall of text>
I wasn't bullied, but my older brother for sure was. My older brother (for the sake of the story I'll call him Gary) was in high school and I was maybe 11 at the time. We did everything together until he went off to college. Back then Gary drove me around everywhere, he was/is a great older brother. Long story short, Gary had a rough pretty rough childhood he wasn't very healthy and a lot of things were difficult for him. He didn't even walk till he was 4 or 5. He is smaller than most, has asthma, and a lot of bullies. He was however, super smart and super quick witted. It might have helped get him in a few incidents. Administration was pretty unhelpful and made it worse in a couple cases. My parents tried moving him to different schools a few times because of the bullying. Gary never retaliated, because he physically couldn't.
I'll remember for the rest of my life the day he was taking me home from school in his brown late 80s model honda civic hatchback. We were down the road at my school which was just down the strip from the high school. As we listened to some terrible late 90s trash radio some asshole classmate of his pulled up behind his car honked the horn until he rolled down his window, yelled threats at him, called him a fag amongst some other pretty hateful shit and then revved his engine as he turned away behind us. I didn't even know what a lot of the things he said, but I was pretty horrified and upset. Gary didn't have an ounce of emotion on his face, save for an slight look of embarrassed since I was in the car with him. I couldn't believe how calm he was, he acted like it was just another one of those normal daily inconveniences and not the WORST thing he'd seen that day. It was like this was normal to him. That was when I realized how bad of a go he had at school.
I was super sensitive to that type of thing after that. I never put up with that shit. Ever. I've had a horrible raw nerve about that type of thing ever since I saw Gary get hounded even while outside of his school.
This was the early 2000s and late 90s and I'm not sure if policies are the same today, but at that time it was pretty standard that you were suspended if you even fought back to defend yourself in a school fight. There were no fights on public school campus...period.
I've been in three school fights in my life. One while at each new school after our somewhat frequent moves. One thing I learned is that there will always be those awful people that will see what they can get away with and test you. There will be a group of shitheads at any school. Some kids are just insecure shits with seemingly little human depth. It may even even be a fundamental law of nature.
By the time we settled down at my last school that actually would stick I thought I had figured out how the bully groups of the world operated. I felt at the time that they would test you to see how much trouble you would put up and then eventually leave you alone and move on. However, previously I had never been around all that long to deal with the longterm consequences. After the scuffle at the last school the 'coolgroup bullies' made it sound to the school like I had a real bad temper, most people eventually saw past it, but there was a rumormill about it until I graduated. It's pretty humiliating feeling like people might be walking on eggshells around you. One of my best friends later told me he felt that it wasn't a temper, but more like Marty McFly's sore spot about being called a coward. It didn't matter, because I got labeled a hothead anyway.
TLDR: All of this was to really say that I think this bullying thing can poison you no matter what you'd go back in time and do. Gary got bullied and had to deal with that humiliation and it's various insecurities, and me seeing him go through that made me think that going 180 in the other direction would be the best solution. I really don't think standing up for yourself in the way that I felt I was doing was the best way to go either.