My Eientei strategy is to start with Reimu, Cirno, Ran, and a tank. Reimu's there for PAR, of course, and Ran's there to buff ATK and MAG before switching out for Suwako, who's there to help hit the more-resistant Eirin and Kaguya with PAR. Cirno, meanwhile, uses Icicle Fall to debuff that pair's SPD. Reisen doesn't need to be hit with a SPD debuff since she stays paralyzed, and two debuffs doesn't trigger Buddha's Stone Bowl. With those two slowed, surviving becomes a lot easier. Reimu heals or paralyzes as necessary, and the tank keeps tanking. If single-target heals are needed, Minoriko comes in to do that. Meanwhile, Ran gets called back in for more ATK/MAG buffing. Once she's done, I switch to Yuugi as my tank with Reimu, Nitori, and Sanae. Reimu's still healing or hitting with PAR, and Yuugi and Nitori are ripping Kaguya a new one while Sanae alternates between them with Miracle Fruit. At this point, Kaguya goes down quickly.
With Kaguya down, Komachi gets to come in and debuff the crap out of Eirin and Reisen. Alice comes in, too, and hits Eirin's MAG. Yuugi and Nitori still do most of the attacking, although I'll bring in Patchy and Youmu for a bit if they run low on SP. Suwako gets her fair share of use here, too, as she's in charge of backing up Komachi's PAR and keeping Eirin from acting. The MAG debuff keeps damage down, and if you keep a full debuff on her, you've got a safety net in case she gets off an Astronomical Entombing. And once Eirin's down, of course, Reisen just gets the shit beaten out of her.
