1) Lulz on listing notable users for normal/ghost in the fighting/ghost section, it was a long list so it happens, and I adjusted it :)
But just for technicalities sake, yes Porygon-Z learns Shadow Ball and Gengar learn's Hyper Beam, check bulbapedia's page for each poke.
2) The more versions of this list, the merrier. I'm just keeping the one in the OP text based for copy/paste purposes and the like.
3) When listing pokemon that use the type combos mentioned in the list, we are only choosing the most notable, that is why Rhyperior is mentioned but not Golem (Onix has a further evolution, Steelix). Tad subjective, but you can understand :)
4) Water/Poison has ten resists, so it can't be listed unfortunately. Although if it was decided that we extend the least to under 15 pokemon, I'll add it along with other deleted combos.
5) Cryogonal will be added to Ice/Ground resists.