> Kirlia evolves into Gardevoir if female and Gallade if male, though it also needs the dawn stone for the latter.

This is incorrect; male Kirlia evolve into Gardevoir just as females do. You can evolve a male (and only a male) into Gallade before that happens, but there is no restriction on Kirlia evolving into Gardevoir.

> in real life a maturing animal becomes the same thing no matter where it grew up or what it learned to do

This is false too. A maturing animal in real life may have its sex determined by environmental factors. (And to complete the analogy, there are paired Pokemon 'species' that differ only by the fact that one species is the male or female version of the other one. For example, female Tauros are called Miltanks, and male Miltanks are called Tauros.)