>>43348644>>43348721Humans are in a similar classification to Ditto, they're compatible with all groups but Mineral (because I'm not even sure people know how they exactly work regarding breeding) and the child takes after the mother. So human males can father pokémon offspring and pokémon males can father human offspring.
This also explains human's natural resistance to pokémon attacks, it's an inherent genetic trait passed forward since the rise of the first humans, reinforced through the years as humans cross-bred with the pokémon populations.