These tiny little crabs are so named for their mutualistic relationship with venomous sea anemones, which they carry like "boxing gloves" and use to "punch" attackers. The anemones benefit with mobility, and the crab gains a set of stinging weapons.
Pokétential: any combination of bug, water, poison and fighting would suit this team-up. The anemones could even be modified Lileep in the same sense that Slowbro's symbiote is supposed to be a Shellder.
Undoubtedly the world's spookiest insects, these Halloween-colored beetles have monstrous face-like patterns on their backs and literally bury small corpses - such as mice or shrews - completely underground as nurseries for their larvae.
Pokétential: an obvious candidate for bug/dark, a combination which oddly enough doesn't exist yet. It could also do with a hugely hunched back and mis-matched eyeballs for a classic cartoon grave-digger look.
Large and flightless, cassowaries look comical and cute but are armed with massive talons on their feet, fully capable of maiming or even killing other animals as large as dogs and humans. Of all modern birds, its anatomy is thought to be the closest to that of ancient dinosaurs, and its haunting calls sound like the rumbles of some far larger monster.
Pokétential: with elongated talons and an axe-like head crest, the cassowary would make a much more fun and unusual steel/fighting than, say, some anthropomorphic fox or something. Just saying.
Another troglodite, this amazing member of the loach family is adapted exclusively to subterranean waterfalls in a small number of Thailand caverns. With microscopic hooks coating their enlarged fins, they can easily climb straight up the slimy rocks behind these subterranean falls.
Pokétential: an eerie, blind water type found only in cave systems, its fins could become legs or even wings as it evolves.
Bogleech regulars are well aware of my affection for the misunderstood Blattodea, the vast majority of which are ecologically beneficial and pose no inconvenience to us. Unfortunately, the entire group gets stigmatized for a handful of "pest" species, whose filthy reputation is still exaggeration.
Pokétential: I've waited a long time for a cockroach pokémon, and as much as I'd love to curb their negative image, I'd also love a scuzzy, hairy, bug/dark garbage-eater. An uncannily human shape would be a fun nod to the popular notion of roaches "inheriting" the future earth from man.
Unrelated to jellyfish, the Ctenophora or comb jellies are ancient, bag-like gelatinous animals lined with rows of beating cilia. Almost all are carnivorous, and some produce their own light in the deep sea abyss. The Beroid combs, shown here, are almost all mouth, with specialized cilia for "teeth" deep inside.
Pokétential: it's hard not to say this should be another water/ghost, though electric or even ice might feel equally appropriate.
Some of the world's most dangerous mollusks, these predatory sea snails can catch and eat even fast moving fish with the modified, harpoon-like "teeth" they can fire and reel back in at blinding speeds. These impressive weapons carry a powerful and fast acting venom, even capable of paralyzing a grown hominid.
Pokétential: It might be cool to have another water/poison running around, but I could see this as a land dwelling creature as well. Perhaps a grass type with a tribal "blowgun" motif...or a Magcargo evolution that launches magma "missiles."
COOKIE CUTTER SHARK:
These little creeps are only inches in length, but their terrifying teeth allow them to sneak in and carve out a perfect scoop of flesh from literally anything they want, including whales, larger sharks and at least one human on record. They also glow green over much of their underside, leaving only a small, dark patch which may disguise them as a smaller fish.
Pokétential: a pitifully scrawny little fish with a deranged grin, disturbing eyes, astounding speed and moves like super fang. In other words, exactly the same as the real thing. See? It's only not a pokémon because it's busy already being real.
Neither squids nor octopuses, cuttlefish hover over coral reefs and rapidly change color as they stalk their quarry, even animating color patterns to warp and flow across their skin in a display that may help to confuse prey.
Pokétential: another pokémon capable of changing its own type, but perhaps in a unique new way. It could automatically change to whatever type resists its opponent's most powerful damaging move, or even change type (and color scheme) at random each turn.
This amazing parasitic crustacean destroys the tongue of its fish host as it drains blood, but anchors in its place and can still be used by the fish to manipulate food - the first parasite recognized as functionally replacing a body part.
Pokétential: a dual creature along the lines of Slowbro, we could have a beady-eyed bug protruding from the immense, gaping mouth of some fat grouper-like fish. As it evolved, the fish could become a nearly skeletal ghost type...or shrink until their roles reverse, with the fish clinging parasitically to the crustacean's tail.