Sonic has no priority. He is so fast, he is hard to aim.
You can abuse these things against him.
I do not know it is sort of hard to explain. Typically when a sonic main uses an attack, they are typically stuck in goint for a particular spot. So, if you stay active in moving about, it throws off their aim. And if you can catch him in the laggy attacks, you can punish him. You have nades, so you really never have to approach sonic. You have to push him into coming at you, then being out of the way when he decides to attack.
So typically, go for the lagless moves. If you want to throw out an attack, jab is good. Retreating pivot grabs are good. I always try to avoid sonic and let him approach me and attack only after he did an attack.