It's from the first generation of Pokemon. The egg mechanic came with the second generation.
The first generation even mentions South America, real world references weren't a thing in later generations either.
It make sense when you admit that pokemon is a post-apocalyptic universe
The world was build on the ashes of our and a few references still exist
These bioengeenered monsters probably ended the wars and are now roaming arround but we still remember what was a mouse and some nerd ad the line in the pokedex to make fun of pikachus