Its pretty funny because the Snake matchup is one I myself find tedious for Sonic. Snakes main objective is to limit Sonics movement, and more importantly DO NOT APPROACH!. A Sonic's most preferable scenerio are those of opponents that like to approach a lot, and since Sonic is so good with punishing mistakes and getting good punishes then the risks might not be worth it. Instead you want to make use of your defensive options. Probably one of the most effective options is up b oos, since its fast and can get a sticky on. nading and shielding is good vs sonics that carelesly use spins to approach, and dash attack can get a hit on a Sonic that is dash dancing a bit too close. Dacus is also pretty good to catch players off guard and get them setups (but careful on not using too often). If you notice a Sonic is very grab happy, Dacus and dash attack become more effective in making sonic go on the defensive. As for recovery you may want to nade as soon as the sonic is about to land a hit on you and always be ready to tech the walls. Dont be afraid to use Snakes other normales for walling out Sonic as well, like dtilt, nair and bair. Thats all I have for now.
Edit- forgot to mention that tranq beats out all of sonics specials, and basically makes him slide towards you asleep for a free follow up