Can Alvin G Mystery Castle be used in competition?

I always hear complaints of incomplete code disqualifying this from competition, and I’m certainly no expert, so looking for someone with deep understanding of the game. If I have Rev3 ROM, what exactly are the bugs that disqualify this from competition? Also, I see there is a “Competition Mode” in settings. Does this simply standardize the order of the Mystery Awards, or is there more to competition mode? Thanks!