I’ve always thought it was interesting that certain Pokémon like Golem or Gyarados can learn moves like flamethrower. I’m sure there are plenty of other examples of questionable moves on certain Pokémon, but how would you feel if there was a mechanic that would cause Pokémon types to deal less damage when using certain types of moves? For example, if a water type Pokémon were to use a fire move, maybe it’d deal 10% less damage similar to how STAB would do 10%. Each type would get 1 weaker counterpart. I’m sure there would need to be some sort of workaround for dual type Pokémon, but I think this would be an interesting mechanic and would add a little extra depth when creating a move set.