Really REALLY out of left field thought on my part… but I’m curious to see how you’ll respond or interpret my potentially mad rambling. Since USUM, I’ve never really gotten over the alien-humans from the Ultra recon squad. And as I have now been replaying Pokémon Platinum and stumbled across the ye olde Sinnoh myth of Pokémon and people being one in the same at one point. Which got me to think like “do humans in the various Pokémon multiverse have types?”. Which isn’t too far-fetched in some cases given normal and ghost for alive and dead people, or psychic for those few individuals like Sabrina. But now that there are technically canonical people that took a different offshoot of human evolution AND how some Pokémon types are based on humanesque myth critters. The idea of people in universe being like the fae or fair folk akin to Fairy types or other types could potentially be a viable canon thing given how darn big and infinite multiverse shenanigans actually are. Here’s hoping what I’m sending somewhat makes sense or isn’t too off the deep end!
So… to my mind that depends on what you think type actually is. If they’re somehow baked into Pokémon biology specifically, then the answer is obviously “no, that doesn’t even make sense.” Humans aren’t Pokémon, at least, not in any meaningful way; there are several things that all Pokémon have in common which humans don’t appear to share (I’m not convinced that we’re supposed to literally believe that Sinnoh myth; there are real-world cultures that have similar myths, and we don’t believe those; there are also compelling ideological reasons for a culture that relies on Pokémon training to create a myth like that).
But on the other hand, type clearly has nothing to do with ancestry or evolutionary heritage. Ice-type Alolan Ninetales is presumably more closely related to Fire-type Kanto Ninetales than it is to any other Ice-type. Ice-type powers must have evolved independently several times in unrelated lineages, so there’s no reason they couldn’t evolve again, in a species even more different. So then the question is, where does type actually come from? Maybe there’s a set of eighteen fundamental forces of the universe that Pokémon can adapt to tap into and control. In that case, well, there’s no reason humans from Ultra Space couldn’t have a range of types, but I’m not sure there’s any good reason to think that they do, either. Maybe there is something basic to all Pokémon, which humans lack, that gives them access to elemental forces, and types are just variations of that, which can develop in many different ways, convergent and divergent. After all, Pokémon of one type can usually learn many techniques of other types, but human psychics or spiritualists don’t appear to have the same flexibility. Maybe they’re coming at similar powers from a completely different direction that wouldn’t necessarily give them all the same properties.
Personally – and this is where I veer into the unorthodox – I think that type is something humans made up to describe how Pokémon fight and predict the outcomes of battles. Pokémon don’t have weaknesses and resistances in common because of something fundamental to the physics of the world – they have weaknesses and resistances in common because they happen to have evolved similar powers that do similar things (but often by different means). There is no rule of the universe that says “Grass beats Water,” but most Grass-types can do multiple things that most Water-types do not have an effective defence against. “Type” describes the practical results as they pertain to strategy and tactics, not any underlying truth. And in that case, the answer is… well, humans don’t battle. It doesn’t make sense to describe them as having a type, because type is an artificial system with a specific purpose; it’s like asking how much horsepower a television has. But if humans did battle Pokémon the way Pokémon battle each other, then it would make sense.
This isn’t an answer, because obviously there isn’t one. It’s more… a collection of points that I think you need, in order to decide on an answer and figure out what it would mean. And… that, in principle, will in some way be good. (Is a thing that I hope.)