Yveltal possesses avian and draconian traits. It has large wings and a tail that are red colored internally and black colored externally. It has intense teal-colored eyes with white pupils. When Yveltal straightens its arms in flight, it forms the shape of a Y. Its talons are also Y-shaped. Yveltal is part flying type, and based on the concept of the y-axis.
Yveltal represents destruction, such as natural disasters, while its counterpart, Xerneas, represents new life.
Its form may be a reference to Norse mythology guardians of the Yggdrasil tree: a bird-like creature that protects the top of the tree, this may be Yveltal, a deer-like creature that protects the soil and trunk of the tree, this may be Xerneas, and a snake-like creature that protects the underworld below the tree is Zygarde. It is part of Yggdrasil Trio.
Yveltal starts with the letter Y because it represents the Y axis in the 3D axis of X, Y and Z.