Can Rattata be shiny in Pokemon GO?

At the end of the Season of Mischief in Pokemon GO, trainers can catch a bunch of shiny Pokemon, including Rattata.

If you have a shiny Rattata, shiny Alolan Rattata shows up in Pokédex even though you can't actually get one yet. : r/TheSilphRoad

✨Shiny Alolan & Kanto Rattata.

✨Shiny Rattata , Kanto and Alolan, Pokèmon Go, registered or ultra friends

Pokémon Go Shinies - how to catch Shiny Magikarp, Red Gyarados, and what we know about other Shiny Pokémon

Pokemon GO Shiny Rattata: How to catch Shiny Rattata, Raticate during Pokemon Day Event? - Daily Star

Two shiny rattatas after using a rattata incense, this was a few days ago : r/PokemonSleep

Evolving SHINY RATTATA TO SHINY RATICATE IN POKEMON GO

Shiny Rattata & Shiny Raticate Family! Pokemon Let's Go Pikachu Extreme Shiny Living Dex Series

Evolving SHINY ALOLAN RATTATA TO SHINY ALOLAN RATICATE IN POKEMON GO

Is there a Shiny Rattata in Pokemon Go? - Dexerto