Freddy beats Pinhead as Freddy is not effected by pain.
Michael Myers and Jason would be whoever is faster and can chop off the others head.
Michael would beat Leatherface as Leatherface is stupid and Michael is silent and would sneak attack Leatherface.
Michael may be able to beat Freddy as he has no fears. If Freddy got into the real world he may be able to do it with his claw gloves.
Dr. Loomis could probably outsmart all of them.
Predator would probably kill everyone too as he is invisible.