Question

Does Yawn affect Ghost types?

Comments

Why wouldn't it?

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Because Yawn is normal-type?

Answer 1

There are very few status moves that obey the type chart, and Yawn isn't one of them. It will work on all Pokemon regardless of typing (though it can be impacted by sleep-related Abilities).

Status move (Bulbapedia)

Comments

Are thunder wave and glare in gen 2 still the only ones?

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Glare also follows type rules in Gen III, but otherwise yes -- unless you count instances like Fire types being immune to Will-O-Wisp.

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According to the type chart, fire Pokemon aren't immune to fire moves, so interactions like that have to be programmed separately. I think a normalized will-o-wisp can still hit ghost Pokemon.