So I may or may not have found out something about Sonic, but I highly doubt I did, and even if somehow I was the first to find this, it's not really worth it's own thread.
Everyone knows you can jump out of Spin Dash, but did you know that you can shorthop out of it too? However, for some reason it's timing based instead of based on how long you hold the button. After the initial little Side-B hop, if you press jump the moment Sonic hits the ground but before he starts rolling forward, the jumping attack will be much shorter than normal. The timing is strict though; too early and Sonic will double jump out of the attack, too late and Sonic will do the full jump. I don't think it's frame perfect, but it's certainly hard to do consistently.
It's easy enough to practice on training mode at 1/4 speed if you want to try it out, but people probably already know about this. I'm not sure how it would be useful either. Still neat though/