https://www.speedrun.com/spo?h=16-nick-challenge-NTSC&x=z27e55ok-7891od0n.jqzz7k2q

it's on the full game leaderboards, press the arrow. the new src update makes misc categories weirdly realy annoying to find

Quick ducking involves buffering a duck, then when you see the animation begin, cancel it with a punch. iirc correctly you need to cancel it within 9 frames of the animation starting. I believe there's a section dedicated to quick dodges/ducks near the start of hootey's beginner guide if you want a visual aid

it's also worth noting that, if you plan on submitting to the leaderboards, retroarch is banned for submissions

hi, to answer your questions:

1. In a single segment run, no you aren't allowed to lose
2. snes classic has no additional restrictions
3. this is an excellent beginner guide by hootey: https://www.speedrun.com/spo/guide/gz5h7 The "guides" tab has other guides there which are more up to date with newer and slightly more advanced strategies, but as a beginner, the hootey video will be the biggest help to you.
4. you need a full video to submit to the leaderboard. This includes creating a new file, beating all 16 fighters, and the full uninterrupted credit sequence. I used to run on snes classic, and pointing a phone at the screen whilst playing worked best for me to capture gameplay