I think I just vaguely assumed they were all made-up animals. Like aliens or something. My kids have started to get into Pokemon recently, but I haven't paid enough attention to it to wonder what species they were. So it surprised me to think that maybe PIkachu was a cat all along. Now, of course, I've googled some of the images, and they do look sort of ... random. I think there's a penguin in there, and a dinosaur. But many ... who knows.