i'm practicing for a any% switch run and i was wondering if you have to fight all the bosses or just the final boss?

All 5 have to be beaten in order for the credits to roll at the end

ah okay thank you

This would explain why my run has been refused (boycotted a few bosses)

Nah, your run was for 100 teensies, not any%. So there's not route requirements for that objective other than achieve the goal (100 teensies). The reason your run was ignored, like several other submissions, is that the platform you played on is not loadless, and you didn't provide a loadless time. So it sat in the queue.

DJthed & Samuroleon extremely sporadically (less than once a year) have in the passed retimed runs. If a run is invalid, I'll reject it fairly quickly, but if it's technically valid but not a complete submission, there's a few runs sitting there that fit this description.