Gastrodon, the Sea Slug Pokémon and the evolved form of Shellos. Gastrodon inhabits the shallow tidal pools of the ocean, and its sturdy shell serves to protect its body.
– Dawn’s Pokedex
Gastrodon has two forms, East Sea and West Sea, depending on whether it’s found East or West of Mt Coronet. The forms are pink and blue, which makes me often think that the colours are gender differences (like Frillish or Jellicent) instead of location-based. Gastrodon and Shellos are the only Pokemon with form differences based on location I think (it’s a new thing in Gen IV I guess). Looking closer at its face, Gastrodon has a pretty derpy face, its mouth bending down in a weird sort of frown. Its in-game cry is also rather unique.
Gastrodon is Gen IV’s Water/Ground Pokemon. I quite like that type combination, since it only has one weakness. I have a Gastrodon on my Pearl team (I’m playing through Pearl recently). It’s been quite useful as my Surfer and Water type. While it doesn’t learn Earthquake by level-up, I’m using Mud Bomb as its Ground STAB move.
Stat-wise, it has a LOT of HP, and serves me well as my defensive HP tank. It has good Sp Attack, but is pretty slow (based on a slug and all). It’s one of the few Pokemon to learn Hidden Power (for some reason). Mine has Hidden Power Fire, through experimentation. I wish it had Ice, but Fire isn’t bad I suppose. One of its abilities is Storm Drain, which is made a lot better in Gen V, because it now grants immunity to Water type moves, as well as raise Sp Attack if hit by a Water move.