Wee woo wee woo check ya watch m8s it's more-autism o'clock
This is a Water-type starter idea for an OC region: working name is "Tuckurtle" or "Tuckapin", as a reference to tucking itself into its shell, "tucker" meaning food, and/or "tuck in" meaning to eat + "turtle" or "terrapin," in this case mostly influenced by snapping turtles and red-eared sliders.
They're known in their home region for keeping bodies of water like rivers or lakes clear by eating excessive plant-growth. They also have surprisingly big appetites for their size and tend to instinctively bite at anything new to see if it's edible or not.
Their shells are quite tough, though they can't pull themselves all the way inside. Rather clumsy on land, they're much quicker when in water.
The reason it -- and the other starters -- are given to new trainers is as part of a conservation effort; they've become increasingly rare as pokemon from other regions have moved in or been introduced, and pushed them out.
I've got a fairly clear idea of its evolution line; starts out as a pure Water type, but also takes on a Steel typing as it evolves - making it immune to poisoning, in order to reflect its role in keeping water from being fouled. Its second stage resembles an alligator snapping turtle, and its final form, a cross between an alligator, and an alligator gar.
I know, going with a turtle water starter wasn't terribly original, but it was the strongest concept I could come up with. Still working out a few things with the color scheme, but the rest of the design I'm pretty satisfied with. As before though, I'm always open to suggestions and thoughts.