Hey man, I feel for you. In senior school I was never bullied, you could say I was in the “cool crowd”(you will realise once you leave school, this really does not matter), but I got bullied badly in junior school.
If you are getting bullied specifically because of the yoyo, I would say maybe from an adult perspective, it might be best not to try impress them with your amazing tricks, and keep the yoyo away. To you, your tricks are great, and they probably are, but to the bullies, it is just something to target you for.
Maybe stick to practicing with friends who also are into yoyo, and not with / around the bullies.
Also, let someone know if the bullying is bad. Your parents, and the school need to know.
I wish you the best.