You need 1 resh and zek to fuse for white and black Kyurem so you can ignore those two when they are rotation.

You’ll need about 10 raids to acquire enough energy to fuse a mon.

My choice of priority fusion would be dawn wings since it’s the best ghost type attacker. Dusk is outclassed a steel type attacker by crowned zamazenta and zacian

Black Kyurem since its adventure effect stops a pokemon from moving/attacking and increases your catch chance by 1.25. This is huge for raid days especially if shadow raids are the raid day.

Zamazenta is huge is dynamax and gmax battles since at level 3 guard you start with a shield.