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I just want to remind everyone that the list refers to how GAME FREAK, sees the types. Think about which types are associated with legendaries, psuedos, special Pokémon, Pokémon that are shilled, Pokémon that are seen as cool, etc. Then think about which Pokémon are seen as early game fodder, which types are used as background filler, which Pokémon are used as stepping stones to make other Pokémon look better. Then think about what types those Pokemon are.
And yes obviously there are exceptions, Mega Kang was the queen of VGC in Gens 6 and 7, and Goodra seems like an intentional attempt to make a lame psuedo.