Proud+ https://youtu.be/CLouWLxjWLs
As far as I understand it, the mechanics of the fight are as such:
-boss has high damage resistance to all characters
-every other turn, it'll have an omen up that targets the lowest HP character
-the first time, it applies a buff that lets that character do damage
-the second time, it kills that character, so cancelling it with 24 hits is advisable
-every 200 total hits, the boss will clear those buffs and rebuff itself to reset
Maybe the intended way is to manipulate HP so that multiple characters are capable of doing damage, but given that most heals outside of green pots are partywide, that's kind of hard to get done. I went for something different. Luffy with meter being fed will have 9 hits from his nuke available assuming no double procs, and Tabina/MC's Decimate can round out remaining hits. He does take quite a bit of damage since he needs to be hit by Shackled Fate at least once each cycle. Fraux in an ougi setup has the best healing output available as well as two dispels for the buffs each cycle, and she's an excuse to sac Mugen for two presses of his buffs without fear of him going blue since the omen kills via instant death, not damage.
It's a bit slow since Luffy's the only one doing damage. The grid probably doesn't matter much, though, since all the damage comes from ougis/skills and that doesn't need much juice. The extra max HP helps keep Luffy alive.
No idea if this'll scale to Proud+.
If the recording looks wonky, it's because my new rig has fallen victim to the Edge memory leak bug.