[noobly]

Also, no mention of potential types like Ghost/Normal that have no weakness, or Ghost/Fighting that have complete coverage with their STAB moves. I haven't played in ages, but surely there's more type combinations that are exceedingly OP.

[elechi]

Ghost/Normal does have a weakness. Dark. There is no combination that doesn't have a weakness, anymore. (It used to be Dark/Ghost, but then GameFreak came out with Fairy type, which is super-effective against Dark.)