Ass Pull: The whole "Michael replaced an ambulance worker for himself at the end of H20" revelation at the start. It wasn't exactly a trueAss Pull, since producer Moustapha Akkad had planned the idea to get out of H20's ending ever since they shot it, but even hardcore fans didn't buy it.
It was originally worse; the Michael Myers in H20 wasn't actually Michael, it was an obsessive fan. It may have made more sense, but it would've been a very hard twist to defend.
Alternative Character Interpretation: Michael Myers wasn't in the whole movie. He was there during the opening scene where he killed Laurie but the rest of the movie involved the serial killer fanatic that Myers encountered in the opening movie took his place, while the real Myers is just hiding somewhere. After he killed Laurie him passing the knife to that fanatic could be seen as his way of saying "I'm retired".
Ensemble Darkhorse: Jim tends to be fairly well liked, primarily due to his funny one-liners and style
Freddie, Busta Rhymes' character. Rappers usually get a pass for letting their massive egos run wild on these kinds of flicks because it's impossible to ruin a movie when it's already bad to start with, but using kung fu to lay the beatdown on a legendary and unkillable Implacable Man like Michael Myers was definitely a bridge too damned far.
Sequelitis: This is an almost unanimously reviled film, often ranked as the worst in the series. It's also seen as completely unnecessary, given that the ending to H20 neatly wrapped things up and the writers had to go to extreme measures to retcon Michael's death.