Uknown's hidden power is not a real normal type move. Gengar only learns mean look. Spiritomb and Chandelure don't learn any either i am sure there are more.
According to the German Pokéwiki all Pokémon except for Weedle can learn normal type attacks (letting hidden power count as a normal move)
Spiritomb and Chandelure have a lot of TMs and Gengar's Mean Look is still a normal type move