In reference to this, where I outline a radical condensation of Pokémon’s type chart into just seven attack types (Might, Finesse, Nature, Water, Energy, Magic, Spirit), where Pokémon themselves have no type at all but have weaknesses and resistances by individual species.
So, in regard to these three suggestions – the point of what I was trying to do was have as few types as possible (well, actually, the real point was to think about how I would do a Pokémon game if I were starting completely from scratch, which I’m still thinking about, with a view to maybe writing a long screed of rambling nonsense at some point in the future, but let’s not go down that particular rabbit hole right now). I wanted to see how little I could get away with. So just on philosophical grounds, I don’t think any of these things need to be types. I do think they can be effects that are attached to specific attacks. Sonic I would probably deal with by putting in a Deafness status condition that, say, causes Pokémon to disobey (because they can’t hear your orders properly) and make a couple of Pokémon either especially vulnerable to it (e.g. Zubat, who ‘sees’ with sound) or resistant or outright immune to it (anything with the Soundproof ability, like Mr. Mime). The attacks themselves, I think can just be typeless (which is a thing my system has; they just do normal damage to everything). Wind is similar; I mostly imagined wind-based attacks as belonging mainly to Finesse, with some being dual-typed (another thing my system has – Hurricane as Finesse/Nature, Twister as Finesse/Magic), and all having effects much like the ones you describe; they’re not universally more effective against certain Pokémon, just more effective given certain environmental conditions. Waste… waste is a weird one because one of the ways I wanted to flip things on their head was by having pollutant Pokémon like Koffing and Grimer be vulnerable to Nature attacks, not resistant (not all of the Pokémon that are “Poison” in the existing system, mind you, just those specific ones; other Poison-types could have different vulnerabilities). Poison, like the others, doesn’t need to be a type in itself; just keep it as a status condition that can be worsened or prevented by the traits of certain Pokémon.