Eiki and Kaguya vs 15F Azure Giant's Shadow (Labyrith of Touhou 2 Steam)
This boss has the exact same problems as before (surprisingly good debuff resistance, reliance on Tenshi's inconsistent buff removal, the boss having low delay moves) but now it has the ability to murder you even if you DO manage to remove its ATK buffs, so that's fun. Here's the party layout I came up with:
-Fighting Spirit Tanks: I went with Mokou and Kasen here since both characters have a passive that lets them reduce damage taken the longer they stay out. Both characters also have the ability to inflict ATK debuffs (even if their debuff rate is horribly inconsistent without Reisen in front). Both are reliable once their Rising Spirit passives are maxed out, the hardest part is keeping both of them alive long enough (especially Kasen. If the boss decides to pick on Kasen with normal Attack or Rasetsu Fist at the start, she's screwed). If you're here for advice, I'd recommending bumping their DEF's Library levels to be Challenge Level x 1.2. I didn't do that, but only bc I was sick of grinding.
-Keine / Reimu: Used for DEF buffing / light healing. Keine is especially useful at the start since she has a Synergy skill with Mokou that lets Mokou become even tankier. Because of the bosses ridiculous damage, I had Reimu as backup buffer.
-Reisen: She's essential. Note that even she can struggle to debuff any of the bosses stats.
-Eiki and Kaguya: The main attackers. Both characters have defense piercing SPI attacks so they're very useful. I would have stuck with one of these characters (probably Eiki) but because Gambler drains MP so quickly, I used both characters.
-Sanae: While she's very good overall, you really need here because she can boost SPI damage.
-Tenshi: I don't see how anyone could do this fight (at Challenge Level) without Tenshi. She's the only character at this point in the game who can actually remove buffs. Even if you did use characters like Momiji and Satori (who can ignore the effects of enemy buffs) they'd probably still get overwhelmed because of the bosses buffed SPD.
-Eirin: Was supposed to be used for Overhealing and ATK debuffing but I forgot. I probably should have replaced her with Rinnosuke + Violent Green Rupee for extra rewards.
Just like the previous fight, trying to sneak characters in can be very annoying because of its SPD + low delay moves. You only want to sneak in characters after it's used a high delay move (Earthquake, Great Terror) but if that's not possible (because the boss keeps using Attack or Rasetsu Fist) you can use that time to debuff the boss. Just make sure your Slot 3 and 4 characters are HVY resistant so you can switch in your attackers IMMEDIATELY after its one of its high delay moves.
Music is "Judgement Days" by COOL&CREATE