Beating a bully's ass can definitely work (sometimes), and it can work on verbally abusive bullies as well but of course violence isn't very accepable and it comes with serious risks beyond just getting in trouble.

Verbally destroying a bully is doable at least for some bullies, but you might not be able or willing to go at them verbally in a way that will work, so it might be better to just pretend like you don't understand, smile, and say something like, "Cool, thanks!"

They'll probably get upset, but just keep doing it or start fucking with them in other silly ways until they get frustrated and leave: Make them look like an asshole in front of everyone, because, you know, they're being an asshole.

Alternately, intimidate the fuck out of them either yourself or through a friend: This is risky but I can work. If you aren't physically intimidating, acting crazy can still work pretty well but I'd advise this as a last resort. Intimidation can easily spark a fight if misused and trust me when I say you don't want to get into a real fight: They can have life altering results if things get out of hand.

Orrrr

Whip out your phone and record them every time they start harassing you. If you live in a single party consent state, you can record it surreptitiously. Once you have a good amount of shitty behavior documented, go back to the school and insist they do something. If not, consider pressing charges for harassment - a restraining order would certainly be an effective deterrent. Might be worth considering a lawsuit against the school if the bullying was bad enough and you documented that they did nothing to stop it.

Or

Act as though they do not exist at all: They want attention, deny them this.

The kind of person you're dealing with, the kind of person you are, and the overall circumstances should guide your approach, not every approach will work on every person and in every circumstance.

Good luck, and remember: This shit is temporary, whatever you decide to do, even if it's nothing, try not to let them get into your head. Ten years from now, they won't matter at all to you.