Gyarados

Gyarados is an incredibly massive Pokemon from the Kanto region. It is the evolved form of Magikarp. Gyarados is a dual Water/Flying type. Funnily enough, its pre evolved form, Magikarp, is known as the weakest and most pathetic Pokemon in the world but can somehow evolve into something that is incredibly powerful.

Gyarados can mega evolve, changing not only its appearance but its type into a dual Water/Dark type Pokemon, making it perhaps the only Dark type Pokemon to ever come from the Kanto region.