These burrowing, omnivorous crickets are common throughout the world but especially popular in Japan, even appearing prominently in another Gamefreak series. Males are able to amplify their mating call with a uniquely shaped burrow, essentisally building their own tiny amphitheatre.
Pokétential: there are strangely very few bug/ground pokémon, despite how many other insects are burrowers. Bonus points if it takes a cue from Diglett and never appears outside of its tunnel.
MOSQUITO:
Another ubiquitous insect they've neglected, these specialized flies are usually herbivores, but the females of some species can partake of fresh blood to nourish their developing eggs. Accidentally transmitting parasites such as Malaria, these tiny vampiresses have killed millions of human beings.
Pokétential: a bug/flying bloodsucker is everyone's first thought, but in a pokémon-based ecosystem, a giant mosquito may as well be an electrical energy-sucker. Only females, however, would learn a signature health-stealing electric attack, similar to the grass type "Giga Drain!"
NAKED MOLE RAT:
Along with the furred Damaraland mole rat, these endearingly homely mammals are the only eusocial vertebrates, forming insect-like colonies with distinct "workers" and "queens." They're also essentially "cold blooded" mammals, they're pain resistant and their powerful teeth can tunnel through concrete.
Pokétential: an early-game normal type in the tradition of Rattata, Sentret, Zigzagoon, Bidoof and Patrat, or a ground/steel with gigantic metal teeth? Like Combee, only females might evolve.
NARWHAL:
These small arctic whales are unusual among cetaceans for their unicorn-like "horn," actually the upper left incisor of the male which grows to penetrate his upper lip. Roughly one in five hundred males may develop dual tusks, and females may sometimes develop a tusk themselves. Only a single dual-tusked female has ever been recorded.
Pokétential: I love the pokémon who translate water creatures to sand-dwellers like Hippowdon, Krookodile and Garchomp. Why stop there? A desert Narwhal would be fun, especially with ultra-rare horn variation.
OPABINIA:
Related to Anomalocaris (the basis for Anorith), this surreal prehistoric organism sported five bulging eyes, a tiny mouth beneath its head and a flexible "trunk" ending in clawed "tongs," the use of which is poorly understood.
Pokétential: another rock/water or rock/bug fossil, logically. Like its predecessors Kabuto and Anorith, it could evolve into a full land-dweller, possibly resembling an insectile mammoth with its bizarre snout.
ORCHID MANTIS:
Camouflaged from head to toe, this elegant hunter so closely resembles a flower, bees and butterflies never know what hit them before it starts chewing their heads off.
Pokétential: Yes, I know, Scyther. He's interesting, sure, but he doesn't look a whole lot like an actual mantis (couldn't it at least have had gigantic eyeballs?) and the flower-mimics feel more than distinct enough. Like Sudowoodo, it could resemble a plant without grass typing, perhaps merely having an ability to boost grass attacks.
ORCHID BEE-MIMIC:
Orchid flowers come in a wild diversity of beautiful forms, but many have evolved with a devious purpose: by closely resembling and even smelling like bees or wasps, the flowers fool these insects into trying to mate with them, spreading the plant's pollen without the need to produce enticing nectar.
Pokétential: a pure grass type that looks remarkably like an insect (or even like a specific bug pokémon) - with an ability automatically infatuating any bug type.
OSEDAX WORM:
You have to love an animal biologists have called "zombie snot-flowers." Feeding exclusively on bone, these bizarre worms grow like weeds on the skeletons of whales or even drowned land mammals, embedded in place by "roots" as they spew eggs into the water.
Pokétential: an old idea I had for hagfish would be better suited here - the skeleton of a whale (er, Wailord) animated by a snot-flower horde! This could also reference the legend of Bake-kujira. Otherwise, grass types controlling a terrestrial skeleton. Maybe a dinosaur. Maybe... human?
PHORUSRHACOS:
Dominant predators over sixty million years ago, the various Phorusrhacids or "terror birds" were massive, flightless hunters with huge, sharp and no doubt quite powerful beaks, snapping up smaller mammals and reptiles or picking at large carcasses, like modern carrion birds.
Pokétential: rock, ground, fighting. Pick up to two and give it a beak like a battleaxe.
PHRONIMA:
These rather frightening deep-sea crustaceans live within the empty skins of salps after consuming their innards and slicing off their ends. Females even raise their young within these hollowed out corpses, which they steer through the water like morbid little submarines.
Pokétential: we could begin with a water/bug combo resembling a happy salp with a tiny, harmless-looking bug riding inside. As it evolves, the bug gets bigger, the water typing is suddenly replaced with ghost...and the salp's little face? Probably not as happy.