>>58503883You are correct in one point and incorrect in another.
Let's say you have a place that take cares of the entire Ralts line for whatever reason. Each year, you get 100 new Ralts. They take one year to evolve to Kirlia and then another year to evolve to Gardevoir and Galade. The first year you have 100 Ralts, sure. The second year you have 100 Kirlia and 100 new ralts. And in the third year, these 100 Kirlia would evolve. Unless the number of Gallade is zero, the 50/50 wouldn't work in at least one place in the Ralts line.
If the number of unevolved female Kirlias is the same as Gallades, it would balance it out initially. So if you have 100 Kirlias in a generation and let's say: 45 female Gardevoir, 5 unevolved Kirlias, 45 male Gardevoir and 5 Gallades, you'd be able to keep the 50/50 ratio... for Gardevoirs. But then you'd create an instability for Kirlias. So the next 100 Kirlia would come, but you'd have 5 female Kirlia leftovers. So you would have 105 Kirlia, 55 females and 50 males.