ITT we give new Hidden Abilities to Pokémon that actually fit the flavor.
Hard mode: No creating new abilities
God mode: Abilities that would actually be better than the default

I'll start.
>Rotom: Motor Drive
if you change its Forme, the Ability also changes
>Frost: Refrigerate (it's a FUCKING FRIDGE for christ's sake)
>Fan: Aerilate (an electric/flying type was getting so much use out of Levitate)
>Heat: Flame Body
>Wash: Drizzle but seriously, Storm Drain
>Mow: Sap Sipper