I know whom you're referring to, it's this guy right? I met him multiple times.
There is a fatal weakness to this composition when used by an AI. On the 2nd set, enemy will NEVER attack or rather the chances of the enemy doing an attack is very slim. Reason? Because once all the skills is up, they will just keep casting all the defensive buffs and swaps.
Now, knowing that fatal weakness, you just need to make use of any of your CC skills. What I did was, I just literally made one of the enemy Ninja permanently useless by using Winry's 3 turn sleep and Kane's 2 turn stun, both skills has very low cooldown thus can be cycled infinitely.
The last threat is just the other Ninja where if it's on mid, it will start attacking. My Faye barrier was there to prevent most of the incoming damage which rendered the other Ninja useless as well.
Lastly, removing one of the 2 Faye from the mid tile. I recommend using a Ninja for this one so you can take the tile at the same time upon using the skill unlike knockback skills.
So, with everything said. What just happened is 1 Ninja permanently CC'd, 2 Faye and Lucille kept casting defensive buffs like retards, and the other Ninja sitting on the midtile attacking my Faye barrier. I have 2 units sitting on mid tiles as well, my Faye and my Ninja (after swapping). This resulted to an easy win w/o killing anything.