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Some of these are completely wrong in regards to real-life animal anatomy (What the fuck is up with Abra's circulatory system, Sandshrew's instestines should not go so far back it touches the fucking spine, Caterpie's anatomy does not make sense for an Arthropod), while some disregard pokedex entries or game mechanics (Koffing does not reproduce asexually, or at least not entirely if he really does want to go with the budding route for Weezing).
It's okay I guess. But if two species cannot survive without each other (Bulbasaur), one of them is not a parasite, it is an obligate symbiote. Real life example is the leaf-cutter ant and the fungus it cultivates, the ant can only eat the "fruit" the fungus produces SPECIFICALLY for the ants and the fungus will die if not cared for and fed leaves by the ant. A more extreme example would be lichen.