Are buckminsterfullerene-corannulene complexes actually stabilised by π stacking?
In short, I think the answer is that although the overall symmetry of the buckminsterfullerene is almost spherical, the quadrupole–quadrupole interaction with other molecules with aromatic cycles are local (in addition to the ever-present van der Waals interactions).

I tried to think of a way to exemplify that, and drew the 2D picture below:



In this 2D model, the “double bonds” of the circular structure represent the individual aromatic rings of your buckminsterfullerene (which isn't superaromatic, i.e. electrons are not delocalized over its entire structure; think may be a key point), bearing each a local quadrupole moment (symbolized in the red/blue thingy). The other particle with a quadrupole is close to one of the ball's quadrupoles, and this local interaction dominates. In fact, other interactions maybe be stabilizing or not, depending on the orientation of the individual quadrupoles, but they are weaker that the local quadrupole–quadrupole interaction.