There aren't really a lot of mechanics to worry about for this challenge stage. The main thing to take note of, is the main boss will periodically deal AoE damage and apply a DEF buff onto itself, making DEF Shredders a strong choice. In addition to this, smaller enemies will also spawn throughout the fight; you can choose to ignore these mobs as if the boss is defeated, the stage will automatically end.
Since the boss applies a DEF buff onto itself, we will want a DEF Shredder such as Akane or Maki. You can then pick out any Piercing Single-Target damage dealer in your roster to clear the stage. Then, fill out the remaining slots with support, tanks, or healers as needed. If you are struggling to survive the smaller enemies that are spawned throughout the fight, feel free to bring an AoE damage dealer.
Note that characters listed here are only some of the viable options
Piercing Single Target