Do You Need Shellder to Evolve Slowpoke?

Hope you like it. TL;DR Shellder isn't necessary for Slowpoke to evolve. But rather, the "shellder" is just calcified armor around newly awakened brain cells.

What item do you need to evolve slowpoke?

Instead of using a special item, you need to catch 30 Poison-type Pokémon while the Galarian Slowpoke you want to evolve is set as your Buddy. Once you have captured the 30 Poison-types, you can use 50 Slowpoke Candy to evolve it.

How do I evolve slowpoke?

To evolve into Galarian Slowbro, Galarian Slowpoke needs to be set as your buddy Pokémon. Once it's set, you'll need to catch 30 poison-type Pokémon. When you complete those requirements, you'll need 50 Slowpoke Candy to evolve it.