Both forms of Shellos were first spotted in Pokémon GO for the first time last month. Originally from the Sinnoh region, the Sea Slug Pokémon comes in two different forms – West Sea (pink and white) and East Sea (blue and green). It can be given 50 Candies in order for it to evolve into Gastrodon, which features an appearance that is influenced by which form of Shellos it evolved from. Despite their initial appearance, Shellos stopped spawning temporarily in Pokémon GO, but both forms have since made a permanent return.
Pokémon Blog 