I'm really hoping for a new revised type chart this next CoroCoro because I'm just raring to find out how the all the other types fair against Fairy in terms of weaknesses and resistances. Hopefully they'll have revised a few of the old types on the chart too (I don't even think I need to mention one of them). And it will finally dispel all of these numerous disputes about Fairy and Dark.
In my opinion, I can't hear anything, and I doubt they'll create more different sounds for 4x and 1/4x effective. Obviously GF used Hydreigon and not Haxorus or Druddigon so it would create speculation like this though. All we know is that Fairy hits Dark for normal damage at least
The fact Dark has only two weaknesses, and one of them in common, is actually, In my opinion, one of, if not the type's best asset, as its hardly the most hard-hitting type in the game. If it were to gain another weakness, they need a way to counterbalance it like introduce stronger dark-moves or make them super-effective against each other, which has been mentioned a few times previously by others.