>>20136419He was joking. There's no "Mixed Race" Pokémon, they will always genetically take after their mother.
A Male Houndoom mating with a Female Luxray will produce baby Shinx, NOT Houndour.
Babies, if bred right, can inherit traits form their fathers, like special attacks, or the Nature, thus strengthening the offspring, but there will never be a "Houndshinx"
In the Image, Dawn is obviously the female, so the joke is, even if fucking Luxray could get her pregnant, she would still give birth to humans.