Grookey's evolved form: Thwackey
When Grookey hits level 16 he'll evolve into Thwackey. Again, he's a thoroughbred Grass type, weak against Bug-, Fire-, Flying-, Ice- and Poison-type Pokémon and moves and strong against Ground-, Rock- and Water-type Pokémon and moves.
Scorbunny's evolved form: Raboot
Raboot is what you get when Scorbunny hits level 16 and once again it's Fire-type only with the same strengths and weaknesses as Scorbunny. Raboot is therefore strong against Bug-, Fire-, Ice-, and Steel-types, and weak against Water-, Rock- and Ground-types.
Sobble's evolved form: Drizzile
Sobble's mean streak becomes apparent once he hits level 16 and evolves into Drizzle. This drizzly lizard has the same strengths and weaknesses as Sobble (effective against Fire-, Ground- and Rock-type Pokémon; not effective against Electric-, Grass- and Dragon-type Pokémon), but looks 735% more ready for business.
Finally, we reveal the third and final forms of the three Pokémon Sword and Shield starters on page 3. You've been warned...