Artist RJ Palmer has been doing the whole “realistic Pokemon” thing for a while now, but it’s usually been a case of “oh wow that’s neat”, not “ahhhhh God I’m never going in the ocean again”.
https://kotaku.com/the-closest-youll-ever-come-to-seeing-a-real-pokemon-m-510229848
His latest work is the legendary Pokemon Kyogre, who is normally a pretty sleek, futuristic-looking fish, but who is now a monstrous flesh-devouring beast of the deep.
You can see the full-size image, and more of Palmer’s work, here
(And yes, there are regular fish in Pokemon)