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Pokemon's variety in designs is literally it's biggest selling point and a massive part of it's global success. Every single gen has a variety of artists working on them, some of them greenhorns, some of them who've been there since the first 3 gens.
This isn't even a complaint, this is you bitching that you can't fit the entirety of the Paldea dex's designs into a neat and tidy aesthetical category like those shitty "what if Pokemon was introduced in (x) generation" drawings.