Beat Frankenstein:
To beat Frankenstein, command your entire party not to attack at all. Take control of Sundano, and stay away from Frankenstein. After a while, you will see Frankenstein's shoulders slump. This means he is about to lift and throw a generator. While he is holding the generator over his head he is vulnerable. So, when you see Frankenstein's shoulders slump have Sundano summon his white tiger. With the right timing, it will attack Frankenstein while he is holding the generator and knock him down, causing tremendous damage. While he is down, you can hit him.

Thanks to Revolution reader GruvieGulie!