How to Complete Grounded!
You only need to defeat Genius Ed to complete this quest. The law forbids Harming the Weak, which means that if any of your units do damage or cause debuffs to units of same or a lower level, you will break the law.
Before you choose your units, you can move the cursor around the battlefield to find out what level the enemy units are, then choose units that are all lower than the lowest enemy level. But if you have been leveling up your units a lot, you might have no choice but to break the law.
Keep in mind that the law also applies if you attack your own units, so be careful if you are thinking of attacking your own units for strategic reasons.