[Alt Text: A clay Pokémon, Wooper, sits on a table with it's mouth wide open full of pills. Caption by Twitter user at sign Serena Harumi says, "Ambi bought me this Wooper candy holder and the first thing I do is stuff its mouth with estrogen"]
Hello little gay people in my phone! It's a joke, don't store your pills outside of it's intended container. Open air is bad for pills.
if they're based on amphibian or reptile biology, is not uncommon for them to change gender due to environmental factors either as they mature or some even as full adults.
one common environmental factor is being bitchless, also known as a sausage fest. this can cause a large percentage of a snake population to transition to fill the gap.
I think the closest biological analog is mammals, actually. They can have the ability Thick Fat for example.
I think it's just a coding error that they never fixed between editions (my headcanon is that some employees fought for it to be kept it). They're not called Game Freaky after all.