The photoionization cross sections of small fullerenes (C₂₈, C₃₂, C₄₀, C₄₄, and C₅₀), and the outer and near-outer shells of atoms (noble gases, alkaline earth) confined endohedrally inside a C₆₀ molecule are calculated employing a time-dependent local density approximation formulation. Plasmon and confinement resonances are found to be a general feature of these cross sections, and dramatic interchannel coupling effects, significantly increasing the atomic cross sections, are exhibited in all cases in the vicinity of the C₆₀ plasmons. Hybridization effects, the mixing of the atomic and cage bound state wave functions, are also found, but no systematics of the hybridization present themselves. Also, in the case of Ar@C₆₀, Inter-atomic Columbic decay (ICD) has been found and studied.