I was that snowflake child who was always teased, and it was horrible being like that. I sometimes wonder, why did it happen to me so much, and why did it bother me so much? My guess is that I wanted to be liked by everybody, and if someone teased me, I took it to mean they disliked me, so I overreacted to what was intended as affectionate teases, which everybody did to everybody, and was then identified as an easy victim. I think my problem was that I didn't understand the difference between affectionate teases, such as "you numpty", and ones which were really not nice. I tended to react badly to a lot of small things, such as losing a game, and had to be taught not to.
The perpetrators quickly latched on to the fact that my usual reaction was to cry over small things. And bingo, the adults told me "just ignore them" or "don't let them do it". A teased child who tries to follow that advice might dutifully remain silent, while being totally betrayed by their body language, which would bring on teasing all the more. My younger brother used to deliberately wind me up all the time as well; it didn't occur to me to do it back to him, because in my world everybody would be nice, and never tease anybody, ever. I feared confrontation, so I felt I wasn't allowed to defend myself. (Having met up with him recently, he said "wow, you're really assertive now!".)
I only remember one time at primary school when I really asserted myself: and that was not about being teased, but about the whole year group being kept in because of the misbehaviour of a few. I stood up and announced my displeasure about it loudly and clearly (I was 9). A teacher took me aside and eventually talked me down. I suppose I felt safe asserting myself to a teacher, in a way I didn't with the other children; but it reinforced the idea that I wasn't allowed to speak up about something I felt was not right.
I think that what might have helped me could have been role play, being taught that you're not going to like or be liked by everybody, being taught to stand up for myself with dignity, making witty comebacks (easier said than done), saying a very firm NO, and practising saying "that's not very nice", in a firm tone. As a child, I thought only adults were allowed to do that. Seriously! Nobody actually taught me that I could do it for myself. Eventually I survived by making witty comebacks. But there was a strange moment as an adult when somebody who really cared said to me "why are you letting them say such nasty things to you?". The truth was, I hadn't even noticed that that person was saying nasty things! I'm not sure if that's a good thing or not.
Certainly, nasty bullying (e.g. racism) does need to be dealt with by the teacher, as does persistent teasing. But I think some children need to be taught the difference between affectionate teasing, where both sides laugh, and nasty teasing, as described here, when the perpetrator knows the victim doesn't like it. I found it very hard to break out of the role of always being teased, and suddenly say "NO!!! I won't put up with this", or to ignore it, and not be betrayed by my body language. There are lots of threads on MN which say "people don't like me any more now that I'm assertive".