The second. But, as far as I can tell, the only moves worth using are those that (almost) entirely ignore the stat in the first place... Super Scope has better damage then I notice people getting with Master Sparks, as far as I've seen (which, admittedly, isn't a whole lot) and it did almost nothing at full buffs and a few levels of overheat with low boss def. The other people in my team couldn't do anything either, even though Kogasa was hitting terror pretty well.
Of course, Leaning Iron Mountain is out, because of high nature resistance. Rumia, Utsuho, Kaguya, and Satori come to mind; especially if you can combo Satori with Rumia so they can stack their damage-boosting skills together, I think (Satori boosts the dark weakness damage and has superior MAG for Rumia's skills, while Rumia grants humanoid boost)
I haven't gotten around to actually beating the fight, though. Testing out Mokou as a buff-counter tank went so splendidly that there should be no issues, though- I didn't even need resurrection for long enough that I could have beaten the fight if I had any offense (overheating lv32 didn't work out) and I could've gone way longer if I had given
the Expansion of Consciousness passive. I might bring in Minoriko for being well-suited to this specific situation.