I took the liberty to put this picture to the Stages Gathering pool and add the stage_connection tag since Patchouli, Aya and Minamitsu are Stage 4 bosses.

Heldrik said:

I took the libnerty to put this picture to the Stages Gathering pool and add the stage_connection tag since Patchouli, Aya and Minamitsu are Stage 4 bosses.

The rule states that there must not be odd one outs. The three you mentioned are indeed stage 4 bosses, but the others aren't, and not one of them come from the same stages, so this pic doesn't fit.

If, for example, the pic contains three stage 4 bosses and two stage 3 bosses, then this pic would qualify for the pool, but if there is only one stage 3 boss in the pic, then it doesn't.