Okay, so this is my finalized Walpurgisnacht raid team. I can reliably do over 400k damage total on levels 13 and 14, and over 200k total on level 15. I would love to do a Mami-less team since more ults ends up hurting you at the higher levels, but her and Moemura are the only built up speed buffers I have, and you need a speed buff. Maybe a built up Santa Sayaka could work since she also buffs dmg and speed (and gives extra SP), but mine's only at A0. I did test out Mabatwo in place of Pluvia and she seemed pretty decent so long as she stayed invisible, but mine is only at A0, so she was definitely weaker in terms of durability than my Pluvia. Normally I'd try Mifuyu as well, but tbh I think she's far better served being Iroha's support in this instance.
This is a good alt, but it's not auto-friendly in the least. Partly because Mel, and partly because I need to be in control of when Kaede uses her battle skill and who she uses it on in order for Yacchan to receive the damage dealt buff. I haven't tried Diroha/Mel/Iroha/Mami/Yachiyo, but I imagine it's just as viable.
So long as you avoid the magic trio, you should be fine. Walpy's first counter-attack gets triggered at 18 ults, and you're going to hit that VERY easily with Kaede/Mami/Pluvia, and I'm pretty sure Walpy's counter inflicts more ailments at the higher levels (need to actually check), so best to avoid that combo altogether.
