This is the fight against the secret boss in The Desolate Hope. To fight him, beat the game then access the Battle Simulator back at the station. Instead of being pitted against the Target Dummy as usual, you’ll go up against Dummy’s Revenge!
Dummy’s Revenge doesn’t have any special attacks, he just one-shots your characters on a regular basis. Use a combination of Malenz’s “Quick Repair” and Mirad’s “Revive” to keep the team alive, while using Bio-Beta’s “Duplicity” to increase your dodge chance. He is immune to slow and stun, and you can’t hack his stats, so just focus on dodging and reviving. Proto-Wall can deflect the hits, and using Blindness will work for a few seconds which is just enough to dodge one hit.
Also, keeping the minigames active is important to provide a steady stream of bar refills. Set the minigames to provide speed and attack power, since defense and life refills will be useless.