Clamperl is unique among Pokémon for evolving by trade while holding one of two different items: a Deep Sea Tooth produces Huntail, while a Deep Sea Scale produces Gorebyss. Its pearls amplify psychic power and are prized ten times over those made by Shellder.
Clamperl debuted in Clamperl of Wisdom on Maisie Island, where a Spoink that had lost its pearl took a blue pearl made by a Clamperl from Isaiah's lab, setting off a conflict with the Bivalve Pokémon. In The Evolutionary War, trainers Nancy and Keith each owned a Clamperl that evolved during the episode, Nancy's into Gorebyss and Keith's into Huntail.
Clamperl's first card appeared in Hidden Legends, illustrated by Kagemaru Himeno, followed by Legend Maker from Sachiko Adachi. Great Encounters, Primal Clash, Celestial Storm, and Fusion Strike each carried new Clamperl art, and Destined Rivals added both a Common by Miki Tanaka and an illustration rare by Mori Yuu in the Scarlet and Violet era.
Clamperl's first card, a 2004 Hidden Legends Common illustrated by Kagemaru Himeno
A Great Encounters Common illustrated by Ken Sugimori
A Destined Rivals illustration rare by Mori Yuu
Clamperl evolves into Huntail when traded holding a Deep Sea Tooth, or Gorebyss when traded holding a Deep Sea Scale.
Yes, it is the only Pokémon that evolves by trade holding one of two different items.
Yes, Destined Rivals #195 is an illustration rare Clamperl by Mori Yuu.

パールル
Water
Clamperl is the Bivalve Pokémon, a Water type that evolves into either Huntail or Gorebyss depending on which held item it is traded with. In the anime a Clamperl's blue pearl sets off a dispute with a Spoink, and Destined Rivals added both a Common and an illustration rare by Mori Yuu.
ClamperlHuntail
No published index yet — too few of Clamperl’s cards trade often enough to strike one.