This card was included in the Secret Wonders expansion, first released in the Japanese Shining Darkness expansion. A Cosmos Holofoil DP-P Promotional version was available in Japan as part of the Trade Please DP event held at participating store chains from November 4, 2007 for as long as stocks lasted. Visitors could trade any 1 Pokémon card (including International cards and Japanese cards with a classic reverse) with attendants for 1 of 5 promotional cards at random. Trainer cards and Energy cards were specifically excluded from the trade. A special variant of this card was available at the Pokémon exhibit at San Diego Comic Con between July 23-26, 2008. The card features the event logo. A gold foil stamped "Staff" version was also given to those overseeing the Pokémon exhibit.
The "West Sea" part of Shellos's name is a sub-categorization in order that this card can only evolve into its respective Gastrodon form.