Though twenty feet from head to tail, up to half of this ancient reptile's length was due to its incredible neck, with only ten highly elongated vertebrae. It's believed to have clung to rocks or logs with its stout, muscular body while reaching underwater to snatch fish in its interlocking teeth.
Pokétential: amphibious? Reptilian? Another starter-worthy water type! It could be stylized to resemble a fishing pole, perhaps holding its neck upright while dangling a long, hook-tipped tongue.
This famous parasite is essentially a whole chain of repetitive bodies, anchored to the intestinal wall by a barbed scolex often mistaken for a "head." There is no head, and we aren't really sure which end should be considered its "front." Without a mouth or digestive system, it simply absorbs nutrients from the pre-digested food of its host.
Pokétential: parasitism is grossly underrepresented in the pokémon world. What if this could be attached to another pokémon, like an item, causing both positive and negative effects in battle?
Also called "water bears" for their bear-like shape and movement, these adorable microscopic arthropods are capable of surviving greater extremes of temperature, pressure and radiation than any other known animal, reducing themselves to a mummy-like state of hibernation.
Pokétential: a tiny normal, bug or water type who can't do all that much...except perhaps return to full hit points a few turns after fainting, though each time would add an extra turn to the counter.
Famous as those weird little bugs who can magically eat wood, termites are actually highly unusual cockroaches with specialized castes. Some species build towering cities with complex architecture, some farm their own edible fungus, some have soldiers who explode and others can squirt an organic glue from their nose-like protrusions.
Pokétential: I'd love to see a social bug type with an actual caste system; breed a queen with a king, and you could get a random variety of genderless workers and soldiers of various possible types.
(Photo source) These tiny, well shielded beetles are often vividly colored or even a shining gold, though some can change their color in an instant. In stark contrast to the adults, the spiny, mottled grubs carry large wads of their own dried feces to discourage predators.
Pokétential: a spiny, poisonous, filth-caked worm could surprisingly evolve into a brilliant golden beetle with extremely high defense stats. Oops, I forgot to add anything to the real animal again! Who needs to?
These highly unusual octopuses (yes, for the last time, that is the correct plural!) are highly dimorphic; the tiny males live only to mate, while females can grow quite large, and unfurl a beautiful "cape" of delicate skin to confuse predators. They'll also defend themselves by ripping off and carrying the venomous tentacles of guess who. Will Tentacruel's suffering never cease?
Pokétential: we have one octopus pokémon, but like the mantis issue, these would lend themselves to a very different creature. The "cape" could even give it a strangely humanoid stance, though only at first glance.
This amazing ten foot bloom is properly called Amorphophallus titanum for its phallic appearance, but the legendary Sir David Attenborough chose to call it Titan arum for television. I like Amorphophallus, but I like David even more, so Titan arum it is! Like the Rafflesia (Vileplume) it also goes by "corpse flower" for its fly-attracting stench.
Pokétential: redundant with Gloom and Vileplume? Maybe. Redundant with my stinkhorn ideas, too? Who cares? We have lots of sweet smelling grass types. It's time for carrion plants to shine.
Another form of polychaete like the "Bobbit" and "pig butt" worms, tube worms live stationary lives in their protective tubes, reaching out to catch food from the water - unless they're hydrothermal tube worms like these, which grow up to ten feet in height near highly toxic, boiling hot deep-sea vents. Mouthless, they're nourished by the by-products of bacteria living in their bodies, sustained by the surrounding heat.
Pokétential: the single most appropriate candidate for water/fire, we could have a whole colony of these creatures resembling a huge hydra. We could call it Hydratherm!
A classic icon of the wild west, "tumbleweed" can refer to a variety of plants which eventually dry up and detach from their roots, rolling about in the wind to scatter their seeds.
Pokétential: in Japanese youkai lore, the Tutikorobi is a perfectly round, hairy beast which rolls over its victims, sometimes portrayed with bear-like arms or even an elephantlike trunk. This already sounds like a tumbleweed pokémon, which could be grass/ground or even grass/flying.
UPSIDE DOWN JELLYFISH:
These peculiar jellies spend almost their entire lives lying upside-down on the sea floor, exposing their mildly venomous tentacles to the sun's rays. Green algae growing in the tentacles themselves provide nourishment to the jellies without the need to actually "eat."
Pokétential: this would make the third jellyfish-like pokémon after Tentacool and Frillish, but how can you resist these guys? This is what they literally do.