yeah, you see the numbers in the bar with your amount of ki, well thats your power level. When you choose your character it will tell what level they can turn ssj etc.. and at what lvl they can perfect it (turn ssj etc.. within less than a second) once you reach the required level press z or x (one of them) by default to turn ssj and there is a button to turn off ssj, just go configure your own set of controls