Pokemon Company will give you one of the 3 Pokemon starters from the Pokemon Red & Pokemon Blue editions to launch the "Pokemon Home" app. So you have a choice of Glumanda, Bisasam or Schiggy.
However, this only works the first time you log into the "Pokemon Home" app. This is obtained for the Nintendo Switch, Android and IOS.
With this app it is possible to transfer Pokemon from other versions as long as they are available in the Pokedex of Pokemon Sword and Shield.
If you don't want to transfer your Pokemon to sword and shield, you can also easily save them in the cloud.
In the app you also get Pikachu, also a reward Pokemon for the first exchange is available, this is a Rotom.
For a full list, click here.