>>47875127See the wording on that's strange. Pokemon is all about interspecies breeding, as Pokemon Species are a thing as there are 896 different species of Pokemon. They also have their own categories for almost each one.
Pokemon egg groups magically unify Pokemon to being able to be bred with one another. So its more like non-egg group based Breeding isn't/is possible. The fact that a species of Skitty can breed with a species of Wailord speaks to the absurdity of Pokemon. Personally, with such a drastic difference in body types like that, it wouldn't surprise me if there is a way to get two pokemon of different egg groups or a Pokemon and human to have an offspring together.