We studied the valency and spin behavior of M = Mn, Fe, Co, Li, and Al in the high-temperature superconducting compound Bi 2.15 Sr 1.85 Ca(Cu 1−z M z) 2 O 8+δ (Bi-2212) for small values of z. Mn, Fe, and Co retain their magnetic moments, and our thermopower and magnetic susceptibility data imply ionization states Mn 3+ , Fe 2+ , and Co 2+ , while Li and Al are accommodated in the charge reservoir layers. Single-crystal studies show that the susceptibility of Co 2+ ions in Bi-2212 is strongly anisotropic, with a weak anisotropy detected for Mn 3+ and none for Fe 2+. Fits to a pseudogap formula for a pure Bi-2212 crystal suggest that the spin susceptibility of the host compound is more anisotropic than previously realized. Data in the superconducting state allow us to compare the pair-breaking properties of the different impurities. Several aspects of the data, including the stronger suppression of the superconducting transition temperature T c by Co compared with Fe for underdoped and optimally doped samples, show that the d-level structure of the magnetic ions and multiorbital effects are important. We also find that the temperatures of the magnetization crossing points are equal to the low-field T c values to within 1% or 2%. This agrees with a 2D thermodynamic fluctuation argument given by Junod et al.