The only version of MTPO I can access is on Arcadespot.com but frontends aren't allowed so I just wanted to know why
I believe it has to do with the way they emulate and frames. It ends up not being 100% accurate emulation. The emu's listed in the rules are all great and I would definitely recommend using them over a website. Also take my response with a grain of salt please. I'm not entirely sure.
building off what he said, im wondering if the emulator over at retrogames.cc is allowed. https://www.retrogames.cc/nes-games/mike-tyson-s-punch-out-usa.html