u/Hieiku

I'm trying to breed Varoom for IVs. But it won't let me breed with the perfect shiny Porygon2 that I got in a trade and has perfect IVs. It won't breed with this normal Golett that has two Best IVs.

I looked it up, and it says it's because both Varoom and these two are genderless, but Varoom isn't genderless at all. I literally have an Adamant Female Varoom.

I don't understand this. Can someone please help explain this to me?