Successfully completed the bonus dungeon on the first try. The only downside is that it's already tomorrow morning.
I had all the best character armors and weapons (except the useless ones), and every equipment worthy of use. All characters on 99 except for the most useless ones but even those at 90+. With this, and playing on EASY MODE, completing the dungeon only took
-9 hours of time
-Pretty much every resource on every character except about 3-4 I didn't use.
This is how they each worked out (or not)
Reimu : At the end, down to near 0 MP (she can drain MP when attacking with her gohei so she can't really run out), and 1 bomb. She was one of the most useful members, did good damage, healing and never ran out of MP, although she had to normal attack a lot to refill it.
Lithos : At the end, down to exactly 0 MP. Her natural Divine Barrier was very useful and she was ok for attacking with Kusanagi, but she has absolutely no way to refill MP, so eventually she is down to using normal attacks or has to be replaced.
Nitori: Down to 2 lives, 0 bombs and 8 MP. I used her in the front lines most of the time. She regains 2 MP each turn so it's easy to keep her on max in the first half of the dungeon by passing turns. She was surprisingly durable with 90% divine barrier, I used her most of the time and she had remaining lives at the end. She did nice damage with Rage Eight and elements/slayer.
Byakuren : 0 Lives with 300+ MP remaining. The 2 MP regen each turn is not much but you don't need to spend too much for buffing and can pass a lot. She was quite useful.
Marisa : 0 Lives, 0 Bombs and 78 MP at the end, probably the most useful character in here. Hard to keep her alive, but she does a lot of damage for very low MP costs and gains back MP really fast. Hakkero is really nice here, too. You'll run out of lives before MP so don't hesitate to spend more when she is down to 1-2 lives.
Mokou : 0 Bombs. I used her as a commander and she had 20 bombs at the beginning. Resurrection is always good.
Sakuya : Switched her out around floor 3 when she ran out of MP. She can't recover it and her ability to stop time is pretty much a must have for the last floor if you don't want to skip monsters, so don't use her until then if possible. I guess I should have used the daggers, but forgot she can use them. Never used anything except a 2H sword on her.
Reisen : I used her near the end only, she has a surprisingly high amount of bombs, so if you need to replace a party member with another damage source, she is good. She can do nice damage, too. She was down to 1 MP but still had 7 bombs when I finished.
Youmu : I didn't use her, so I can't say much about her usefulness.
Aya : Didn't use her either. I didn't need to kill the Yukkuris as I had max level already. I think she is useful for the first 4-5 floors at most, after that, all the enemies are minibosses with far too much hp, so it doesn't matter there who gets the first turn.
Alice : Also didn't use her. I wanted as much damage sources as possible to save time. Using her would have made survival easier but slower damage*9 hours to complete without her = I saved several hours, at least. I think she can't recover MP either.
Cirno : I only used her in the last few battles when I ran out of better characters and she was useless. Didn't have enough protection to keep her alive either, and she did uninteresting amounts of damage.
Satori : Down to 0 lives and 0 bombs. She had 111 MP remaining. I used her in the first two Seraphim battles, to learn Punish the Judgement and to turn the land element away from light to disable Seraph's regen, and after that mainly to use PTJ to be able to kill faster.
Remilia : Another character I used near the end only. Unlike Cirno, Remilia did some really nice damage while her bombs lasted, but she ran out quickly.
Sanae : Only used her on the last level when I no longer had Byakuren to buff nor any other character I could use in the back row as a replacement magic attacker. She wasn't as good as Reimu but still quite useful. She still had bombs, MP and lives remaining at the end.
Patchouli : I used her on the last floor mostly. 0 bombs and 11 MP at the end but she had 6 lives so I could make some more MP by reading if I wanted to.
Yuugi : I didn't use her. She has low MP and Bombs, so I don't think you can use her for a long amount of time effectively.
About the areas. First five was not too dangerous, a few random minibosses and some dangerous groups of normal monsters, but most of the time it was possible to find a battle where I could refill my MP. The 6th area has the minibosses from Stage 21 paired up in groups of 2. Some of these weren't too dangerous, but others were a lot more so. Have some light damage ready against the snake, it likes to spam death and untankable 10k+ damage attacks. 7th floor has the bosses from stage 27 and the first one is always the Seraph. Some of these are weak enough to pass or refill MP by normal attacking, but others are very dangerous. It's best to clean this floor because if you don't, and have to come through it again, then you have to kill another seraph, and those take a long time. The last floor has the demon and elder dragon you know from the 8 star quests although with different names. These are very hard to kill even if you are prepared to fight them and have all your MP and bombs on max, so reset if you encounter them, unless you actually have all characters necessary to beat them (Sakuya for Quicktime, Reimu fro major light damage, Aya to make sure Quicktime goes off when it needs to, etc). Although the demons seems to appear regularly, it's somewhat random, so you can empty the room eventually by letting the yukkuris run away and killing the less dangerous enemies.
That's all, and there is no way I'll ever do this again, especially not on normal, that's for sure.
Good look for everyone else who attempts it, now I'm going to finally get some sleep.
