>>26691632>>26691612My best guess is because Heatran isnt a one-and-done thing, it's just a Pokemon that dwells below the earth's surface, within the molten rock and magma (redundant, I know) under the Crust. So theres BILLIONS of them, but its impossible to tell how they breed, since theyre extremophiles.
>>26691519Because, like Starmie, Meloetta is two genders.
Pirouette is male, Aria is female. (Starmie might be based on how a Starfish can latch onto a partner starfish in copulation, as such one is male and the "other" star is the female, thus the collective 'mon has no gender)