Level up Slowpoke to level 37 to evolve it into Slowbro
Use a Galarica Cuff on Galarian Slowpoke to evolve it into Galarian Slowbro
Use a King’s Rock on Slowpoke and trade it to evolve it into Slowking
Use a King’s Rock on Galarian Slowpoke and trade it to evolve it into Galarian Slowking