Unfortunately with bullying it's a bit of a tricky situation to handle, not to mention a... well, situational situation.
In the CMC's case, really the best thing they can do is what they're already doing: ignore it. Especially since DT and SS are, while admittedly abusive little bitches, not actually doing anything
wrong. The spirit is there, certainly, but since they don't ever directly name call - at least not in front of an adult in authority of them - they can't realistically be called out on it.
Physical bullying is a different issue altogether, but it's not one that looks like it would appear so it's difficult to focus on it without shoehorning it in(For the record, in regards to physical bullying: It's the same issue, really. A teacher cannot, realistically, do anything about an issue without evidence. It's good to tell a teacher because they can keep a watchful eye out from then on, but they still need to SEE what's happening to do anything. This includes the issue with fighting back - if they only hear that there's a fight going on and they have no way of telling who started it, they have no choice but to punish both parties. Think of it similar to the actual legal system; We need to investigate the whole issue otherwise real justice would never be done. n this case you need witnesses, but as kids are pretty notoriously biased you often have to write out their testimonies.
For it's easy for us, the victims of bullying to talk about how little teachers do to stop it, imagine it from the teacher's perspective. Almost all teachers are genuinely good people who care about the kids under them. Imagine how ungodly frustrating it must be to KNOW that a kid is being hurt and being unable to do anything about it because of the system.
The best thing you can do is to game the system, and avoid it all together. Bully wants to start a fight on school property? Let them, and don't fight back. When the teacher gets called the evidence stacks against them overwhelmingly, and the teacher maybe CAN do something. Outside of school property?
Kick their little asses into oblivion. The easiest way to get rid of a bully is to make them fear the consequences. Get them in trouble when you don't fight back, and give them hell when you do. They fear both winning and losing.)
On a cheerier not regarding Ponyville's size: At least in Canada a town doesn't qualify as such until it's population reaches 5000 in and around the town. Coming from a town that
just qualified, I can tell you that ponyville does not. Thus, it qualifies as a village, the next step down.