There is no point in having a run for each boss. The beginning would be the same for each run. And if you were to run until e.g. Hermie III or whoever, then those runs would involve glitches too if you want a fast time.
Sorry but I don't think you're getting around the glitch, either you learn it or you play the game without it. Only other category I know of is acquiring all the coffee items, but I'm not sure if that involves the glitch or not.
If you get the japanese version, you can barrel clip horizontally through walls easily in that version which you can't in the English version. In other words, the glitching is somewhat easier to do on the jp version so you might want to reconsider and go for a glitch category using the jp version. It costs about 30 or 40 $ on ebay or other sites, or you emulate it in bizhawk (mgba core).
Would a final boss only category seem likely? Granted, there's not really a whole lot you can do, but i see a good bit of people who like to beat the final boss as fast as they can. my current time is 1m 11s but I'm sure people can find ways to beat it faster. of course it would start from the start of the Bowletta fight and end when the death animation for the soul starts. Definitely an interesting challenge whether its a category or not
Thats a stretch to even call an IL. Feel free to challenge yourself with timed challenges for fun. But dont expect something so arbitrary and specific to be added to the leaderboard.
