Im trying to get an Adamant Archen and i want to know whether i can save the game before the egg hatches and turn off the power and try again if it isn't Adamant.
Save before you get the egg. Hatch the egg. If its the nature you want keep it. If not turn off and hatch the egg again. The stats of an egg are calculated when you get it. If you save before it hatches, no matter how many time you turn off and try again the result will be the same.