Who is that Pokémon? (Thur 3)

One thing first (unless they say differently these do not apply to any other persons Guess that Pokémon threads) I want to set up some simple rules: 1 you may look at other comments, 2 you may not guess twice in a row wait for someone else to guess, 3 I will best answer and like the first correct answer and give a hint to all incorrect answers.

Alright here a Pokédex entry of the Pokémon I am thinking of: “It is said that somewhere in the ocean lies an island where these gather. Only they live there.” that entry is from Pokemon crystal.