T-block
B2B TST
Charizard can do okay as well I find. He can't kill you either
Flamethrower is really good in this matchup... it feels really hard for Charizard because it seems like he can react to everything you do, but if he's the type of Sonic that's trying that, dash at him and Flamethrower to hit him with the tip of the flame. It's safe unless he reads the Flamethrower beforehand and dashes early, but forcing him to attempt to read is exactly what you want to do, and makes the matchup much easier.
Flamethrower is really good in this matchup... it feels really hard for Charizard because it seems like he can react to everything you do, but if he's the type of Sonic that's trying that, dash at him and Flamethrower to hit him with the tip of the flame. It's safe unless he reads the Flamethrower beforehand and dashes early, but forcing him to attempt to read is exactly what you want to do, and makes the matchup much easier.