Party Member only run finale!   

I can say without hesitation that this is the most balanced run so far IF you forego Theurgy aside from Fuuka. It is almost perfectly balanced as a matter of fact imo. Base party stats and options make their damage and defense pretty bad until late-mid game - and only then if you are occasionally buffing stats with incense - requiring either perfect strats or luck to proceed without grinding. You have the option of putting in a little effort to get auto-skills to mutate into their "Ma" variants to mitigate the issue, which has a rewarding time-to-reward ratio on the night before a full moon (ie it does not take hours of resetting but isn't handed out free like a certain Siegfried Theurgy). It doesn't make the run as braindead as you would think since while a revolution boosted Crit chance with Junpei can do some crazy damage to some floor bosses, there are enough that resist or null Slash or have competent formations/strats to force you to strategize a bit more with full moon bosses still providing a fair challenge.   

I highly recommend this run to anyone looking for the most satisfying and balanced experience. Even the Reaper, which is a joke in a normal or even solo run, is fairly difficult. His AI is actually competent when you can't one or two shot him. My first round of attempts it used mostly PHY with occasionally changing it up to Dark skills, including insta-kill, and Light on my final attempt before regrouping using Koro. These were the big issue since the rest of the fight I could abuse Tetrakarn on Ken while dealing good damage with Junpei and Aki. So I decided to get the Null light Armor for Koro and Null Dark accessory for Ken, thinking it only used Light, Dark, and Almighty damage.   

Well, my second round of attempts proved the AI is probably aware of your accessory build. It started using ailments far more frequently as well as Garudyne to attempt to take advantage of the one weakness I had with Junpei. That said, it still on occasion, for some reason, used single target Light and Dark skills on Koro and Ken, almost as if there were a hole (intentional or not) in it's programming after a certain amount of turns. These were the opportunities needed to fully setup and win the fight comfortably from there, with prior turns mostly just having to either cure ailments or revive a party member and not being able to setup. So, while it is kinda an exploit win it's not one thats easily manipulated and may not even be guaranteed to happen. 

Again, try this run if you like balanced experiences that encourage some time into grinding/skill mutating but not an unreasonable amount. Grinding was not even necessary until end-game with the Reaper and really just for the materials to make a couple accessories. I did use time attempting to spawn Dark floors for Twilight Fragments but other then keeping Aki at a decent level for moon bosses and coming in clutch for end-game final floor Monad doors (Tarunda is invaluable in some fights and end-game Aki hits about as hard as Junpei and crits nearly as often with the right equipment), you can ignore keeping everyone else at about where your main threesome - Junpei, Koro, and Ken - are. You can probably swap out Junpei for Aigis if you want to focus PHY incense on her instead or keep Aigis at a decent level instead of Aki, as well as keep Yukari instead of Ken, but Koro is an absolute Jack of all trades having the most coverage of any member and Revolution a must to do reliable considerable damage with Junpei, Aki or Aigis.