Which Pokemon generation did the fan-named "Masuda Method" first appear in?

The Fan-named "Masuda Method" first appeared in the Pokémon Diamond/Pearl generation. It is a breeding technique named after Pokémon game director Junichi Masuda, who introduced it. The method involves breeding Pokémon from two different language games, increasing the chances of hatching a Shiny Pokémon. This technique quickly became popular among players looking to obtain rare and unique Shiny Pokémon, making its debut in the fourth generation of Pokémon games.