The Poke Ball Plus was first introduced for Pokemon Let's Go Pikachu & Let's Go Eevee, and it will be compatible with Pokemon Sword & Shield as well. It won't be able to function as an additional controller like is could in Pokemon Let's Go Pikachu & Let's Go Eevee, but players will still be able to take their Galar Region Pokemon on a stroll with the Poke Ball Plus. It also will keep its functionality with Pokemon GO. Furthermore, by using the Poke Ball Plus with Pokemon Sword & Shield, players will once again receive the Mythical Pokemon Mew as a Mystery Gift.
We have questions and answers related to this topic which may also help you: