>>47073108I present to you an alternative to the Sound type that presents far fewer logistical issues for sound attacks and dual type Pokémon without Normal typing.
Music type. The only existing Pokémon who is put into an awkward position by this is Primarina who can be given an ability that enhances Music type moves. Kommo-o, Noivern, and Seismatoad can ignore this type entirely. Meloetta, Chatot, and Jigglypuff can be the only Pokémon to lose a type over it.
