It all depends on the characters you recruit on your team, their level and the skills they possess. Make sure you have Summanus on your team, as most of his "thunder" skills not only deal more damage, but also gain an extra turn.
For example, Static shocks deal moderate damage and gives one extra turn to itself. 20000 volts also gives moderate damage, and you gain one extra turn after using it. 50000 bolts deal substantial damage, plus you gain an extra turn. This way, you can keep attacking the enemy by using each skill, while giving you an additional turn.
His special skill is 10000000 volts as it deals heavy damage to all enemies.