>>11803723 (OP)>>11803748DK and Bowser have the best top speed and everyone uses them for top play.
So the thing with SMK SNES is that it's extremely precise with a decent high skill ceiling. Whether you want to use glitches or not is up to you. It's mostly learning the jumps, slides, shortcuts, and when to use the power ups. The later games are more casual and have more come-back mechanics.
Watch high end plays and time trials to hone down the specifics.
https://www.youtube.com/watch?v=-Kkmw_urxaw