Does anyone know the etymology behind it?
The Masuda method is named after Junichi Masuda, a founding member of Game Freak who first alluded to the feature in his "Hidden Power of Masuda" director's column on the Game Freak website. In a column detailing the various incentives for trading with foreign players via the Global Trade Station in Diamond and Pearl, he hinted that breeding with Pokémon from other countries made it easier to hatch "rare colored" Pokémon.