Are angular momentum selection rules only understood for hydrogen like species?

Question

I am someone with a rudimentary understanding of atomic and molecular physics, and with that I'm trying to understand in which case which selection rule becomes applicable. For the angular momentum selection rules in particular, I see that the Wikipedia article summarizes all the rules in a single table. Before the table, though, it makes the following statement:

Which transitions are allowed is based on the hydrogen-like atom.

Could someone please explain what this sentence means? Is it that all the selection rules listed in the table are only applicable to hydrogen-like (single valence electron) species? Or is it that the table can be extended to any species but that the theory of it stems from the hydrogen atom? Do we know the selection rules for non-hydrogen like species?

Answer 1

I know for certain, that the same selection rules apply for Yb, Sr and Mg atoms, which have two valence electrons. Since the selection rules are consequences of angular momentum conservation, they apply to all species. HOWEVER, if too many electrons are involved, different states may be too close to together, such that the selection rules apply, but the effects can not be observed because it is just a giant mess.

Fun fact: There are also selection rules for molecules involving the vibrational and rotational states of the atoms!