I think this pose is only used once in the entire game, but it was a hell of a moment.
It's just before Reimu vs Sumireko in story mode when Sumireko was threatening to bring down the Barrier.
Just the shear weight of their dialogue gave me the only chills down my spine anything Touhou canon has ever given me.
It's also, I believe, the first time Reimu and the final boss have said simultaneous lines since the old windows era. I don't feel like checking right now though.