It would definitely have to be a Final Girl-centric movie if it were ever to happen.Still goes back to the inherent issue that neither one of them talk and neither one is much of a character. I think that’s what makes Freddy vs Jason work at least a little. Freddy has a personality and doesn’t need someone to narrate his thoughts.
I don’t think your idea sounds bad at all tho. But I’ve got no desire to see those two “versus” each other cause Michael isn’t a character.
Basically it would have to be something like a straight slasher movie for the beginning of the movie with Michael and Jason on parallel killing tracks knocking off counselors and then Laurie realizes someone is murdering people, assumes it's Michael but runs into Jason first and then Michael pops up just as Jason is about to kill Laurie which causes the fight to break out between the two killers over who gets to murder Laurie Strode.