I'm about to start and submit a run of a GBC game with OpenEMU, and I can't tell from this discussion if that's approved or not. I have the ability to get the game itself and use the Gameboy Player for the Gamecube. I just need to know what will be the easiest and best.
For a GBC game, if you have access to a Gameboy Player that is almost always the best/preferred way to run those kind of games unless you really enjoy emulator for some reason. I would ask the mods of the game if they have specific emulator rules or only allow specific emulators, they'll be able to give you a definitive "yes/no".
The game I'm planning to run isn't on the list yet, so I think I would be the mod for it. I can run it both ways just to see if there's a drastic, noticeable difference.
Ahh. Something in my gut tells me OpenEMU will run faster than real console, so it may not be considered valid in that case. For GBC games, Gambatte is much more accurate. I think the Pokemon forums or resources might have a link to a version that is accurate. I'd recommend looking into that too.
Switch - Yuzu (Fewer Games are rendering almost perfectly or perfectly and running at 60 FPS with/without fewest freezing performance are nearly accepted for runs!) :D