If i have a crown in one of my molars and the crown is slightly unfit (bigger than what my jaw allow, just slightly), could braces possibly adjust that to align/fit my other teeth as well or should i get a new crown that perfectly fit before braces?

As crowns are custom made prosthetics, there is no reason that a crown cannot be made to fit in your mouth just right. Have the dentist make you a new crown.

THE CROWN CAN BE TAKEN OUT AND ADJUSTED TO FIT PROPERLY,IF IT DOESN'T WORK THAN A NEW CROWN CAN BE MADE TO FIT IN THE SPACE THAT WILL ALLOW FOR THE CORRECT ALIGNMENT.NO NEED TO SPEND MONEY FOR BRACES.

This is a restorative dental problem, not an orthodontic problem. See the Dentist that made the crown for an adjustment or remake.