  We propose a generalization of the concept of superconducting fitness, which
allows us to make statements analogous to Anderson's theorems concerning the
stability of different superconducting states. This concept can be applied to
complex materials with several orbital, layer, sublattice or valley degrees of
freedom. The superconducting fitness parameters $F_A(\bf{k})$ and $F_C(\bf{k})$
give a direct measure of the robustness of the weak coupling instability and of
the presence of detrimental terms in the Hamiltonian, respectively. These two
parameters can be employed as a guide to engineer normal state Hamiltonians in
order to favour or suppress superconducting order parameters with different
symmetries and topological properties. To illustrate the applicability and
power of this concept we study three cases: the non-centrosymmetric heavy
fermion $\text{CePt}_3\text{Si}$, the hole doped iron pnictide
$\text{KFe}_2\text{As}_2$ and the doped topological insulator
$\text{Cu}_x\text{Bi}_2\text{Se}_3$.
