I knew that the advanced stages of the female Nido couldn't breed, but I wasn't aware about the "only male babies" thing with the Nidoking. That does seem odd and illogical. My guess is that they made some mistake with the coding where a random number within a certain range was supposed to be generated (thus determining the gender of the baby) and they accidentally set the formula up to always generate male babies. That or it's supposed to be a fun little secret that only people who play the game like crazy know about.

Is that true for both GSC and RSE (and I suppose FrLg as well)? It'd be interesting to test that out.

And the upper stages of female Nidos not being able to breed never made sense to me. I just don't get that. That little factoid, however, was about the only useful piece of info I got from a GS guide I bought way back when. It had discrepancies, incomplete info, and it stopped at the Bug Catching Contest. Yeah, that's right. It never continued to Ecruteak City. I'm pretty sure it didn't even get to the Sudowoodo problem.

Moral of the story: Check your guides for completeness before you buy them. Or use GameFAQs or something. Don't get suckered into a [expletive] guide.