Gamefreak released a new video this morning which released some new details and updates from Pokémon Let's Go: Pikachu and Let's Go: Eevee! We got a sneak peak at the encounter with the legendary bird trio: Zapdos, Articuno, and Moltres. It looks legit! We will be able to transfer first generation Pokémon from Pokémon Go, AND their Alolan forms! They also announced "candies" which will make leveling up our Pokémon's stats much easier! Will you be transferring you Pokémon from Pokémon Go? What are your thoughts on the Alolan forms being available? What are your thoughts on the candies?
Probably. I want my ice bird in the game as soon as possible. Though I’ve got one question: do you keep the Pokémon you transfer in Pokémon Go? If you don’t, probably not.
I watched the trailer again and it seems unclear. I would be willing to bet that you don't get to duplicate your Pokémon.