2 best control changes for shtl imo are y to special, so you roll your thumb over x to y, or control pad up to special. Draw back to control pad up is its almost impossible to do a b reversal shtl. Draw back to Y as special is you can mess up and full hop a lot if you don't practice it a lot. I like them both, but I think Im going to use the control pad for the time being until I stop messing up with Y in training mode xD, then I'll switch over.
You could also set a shoulder button to special, but same issue as the y button occurs, plus it doesn't feel natural to hit a shoulder button 3 times in a row really fast.