We seriously need to have a pokemon based off a roadrunner. It'd be kind of like Doduo, I suppose, but with one head. And fast.
While we're at it, why not have a coyote pokemon? I know Mighteyena is kind of life a wolf, but hey. They're different.
A fly pokemon would be cool. Like, a regular fly.
While we're at it we might as well have a mosquito pokemon.
And we don't have enough pokemon love for slime molds and mushrooms. Although they aren't really animals. While we're there I think it'd be cool to have a one-celled pokemon that forms together in a colony to act as one (like the Portugese man of war).
Which reminds me that we need a sea urchin pokemon. Cloyster doesn't do enough. We should also have a sea cucumber pokemon, that would be sick.
And pokemon parasites would be realistic. When you catch a pokemon have a certain chance that a parasite pokemon might come along with it. That'd be interesting. Like a flea, or a leech, or maybe even a tapeworm or something.
And I know it's not an animal (it's a protist), but there is no pokemon for Giant Kelp. That would make a sweet Grass/Water type.
Okay, I'll stop now.