Are Pokémon animals or not?
…probably? Most of them?
I mean, most of them obviously fit just about any common sense definition of ‘animal’ that you might come up with; the problem is that trying to apply scientific definitions to them gives you all kinds of awkward grey areas because those definitions were written with real organisms in mind (also because taxonomy starts to get a bit funky when you’re dealing with stuff as fundamental as “what is an animal, anyway?”). Working with biological definitions here… we can probably assume that Pokémon are eukaryotic (their cells have self-contained ‘organelles’ with specialised functions, which makes them capable of more complex biochemistry) and multicellular, which means they’re not bacteria or archaea. Beyond that… oy. There are three kinds of eukaryotes: plants, animals and fungi (well… and protists, but there isn’t really a proper definition of that group and never has been). Plants and fungi have rigid cell walls (cellulose for plants and chitin for fungi), while animals don’t (just the phospholipid membranes that everything has). Most plants are autotrophic – that is, they can assimilate energy from their surroundings and don’t rely on other organisms for energy – but there are one or two that aren’t… and I do mean ‘one or two,’ because most so-called ‘carnivorous plants’ do photosynthesise for energy; they ‘prey’ on animals specifically for bioavailable nitrogen compounds. To my knowledge, only the parasitic rafflesia (the flower that Vileplume is based on) is actually incapable of photosynthesis, but I’m not a botanist; there might be others. The point is that what makes an organism biologically a ‘plant,’ ‘animal’ or ‘fungus’ in the real world is actually something we can only observe on a cellular level… and we obviously can’t do that with Pokémon. Are Grass Pokémon plants or animals (or maybe fungi, in the case of Shroomish and Amoonguss)? I have absolutely no idea.
The further problem is that all modern taxonomy is (at least, in theory) based on evolutionary lineage – that is, we don’t just group organisms by shared traits, we group them by shared traits which we believe are indicative of common ancestry. We’re pretty sure, for instance, that the idea of a membrane-enclosed organelle is something that only ever evolved once (or at least, was only ever successful once), because eukaryotes seem to share certain other features of their biochemistry that bacteria and archaea don’t, so all eukaryotes are probably more closely related to each other than to any prokaryotes. Now… what that means is that we actually have no meaningful framework for classifying life that didn’t evolve on Earth, assuming there is any. We might find something that acts very much like a bacterium, but if it didn’t evolve on Earth and isn’t related to anything terrestrial, then taxonomically it sort of isn’t a bacterium, even if it makes perfect sense to call it one (this is sort of the reverse of how all birds are technically dinosaurs because of their ancestry, even though common usage of the word ‘dinosaur’ seems to say they shouldn’t be). Similarly, if Elgyem is actually from space and is descended from organisms that evolved in space and never had anything to do with Earth… we can’t actually call Elgyem an ‘animal,’ however much we might want to (or, well, we can call him an ‘animal,’ but we can’t call him a member of the kingdom animalia). You can forget about Deoxys, who supposedly evolved from a virus (viruses arguably aren’t even technically alive because they don’t respire).
So basically the short answer to your question is “I am a fish.”
P.S. Bonus points if you can tell me why that last statement is technically true.