Still think that instead of Fairy they should've introduced Sound and Light, for a ton of reasons.
First of all, there was (and still is) a shit ton of sound-based moves and sounds are an established mechanic within the games. There's also a bunch of Pokémon that have sound-based concepts, ranging from Exploud to Noivern.
We also need to balance certain types. Steel would be weak to sound, because vibration.
Ice would resist light, because it reflects it. Water would be weak to sound, seeing as water carries sound very well, making it more suspectible.
Grass would resist light, plants love that shit. Dark would be super effective against Light, but also weak to it, because logic.
Ground would resist Sound, as it would get absorbed. Dragon would be weak to Light just because that shit needed to be nerfed, makes as much sense as being weak to Fairies. There's more that could be said, but this gives you an idea how they should function.
Honestly, when 6th Gen was around the corner I was SO sure they'd give us Light and Sound. It seemed so certain when I saw that one of the legendaries was a fucking Wyvern, a creature that literally kills by screaming, and the other one was a deer whose antlers reflected all the colors, ie. light.
