https://techcrunch.com/2018/07/23/pokemon-go-what-are-lucky-pokemon-vs-shiny/

Pokémon GO just got a little surprise update, complete with a curious new feature: “Lucky” Pokémon.

Most things in Pokémon GO are adapted from things that already exist in the Pokémon universe. Items like incense, lucky eggs and the like all exist in the main Pokémon series (though what these items actually do tends to be a bit different in GO).