Necrozma

Ultra Sun: It looks somehow pained as it rages around in search of light, which serves as its energy. It’s apparently from another world.

Ultra Moon: Light is the source of its energy. If it isn’t devouring light, impurities build up in it and on it, and Necrozma darkens and stops moving.

Necrozma is a vaguely humanoid Pokémon whose body appears to be constructed out of a black crystalline material.

The large protrusion attached to its head is its tail, which has a row of three large spikes along the top and is white in the back with a dark gray symbol resembling a eight-pointed star in the center.

Its face is actually a prism-like object known as the "brain prism", which possesses a collection of multicolored shapes that resemble eyes. While absorbing light, this brain prism glows white. Its thin arms have disproportionately large hands with three claws. Jutting out of the back of each hand is a whitish crystal that darkens toward the tip, and each elbow has a hook-like spike.

Two large spikes jut from each shoulder and there is a row of smaller spikes along each side of its body. Its feet have three hook-like toes each.

Dawn Wings Necrozma

Ultra Sun: Lunala no longer has a will of its own. Now under the control of Necrozma, it continuously expels all of its energy.

Ultra Moon: This is its form while it’s devouring the light of Lunala. It grasps foes in its giant claws and rips them apart with brute force.

Dawn Wings Necrozma resembles an armored Lunala with Necrozma as body armor. Dawn Wings Necrozma has armor around its torso, head, and certain parts of its wings and tail. It also has a triangular helmet with the brain prism visible, as well as Lunala's own eyes visible as glowing pink lights. Necrozma's arms extend from the center of its chest.

The armor surrounding its body has two large spikes jutting up from around its shoulders and four, glowing pink lights in the center. On its lower back are two thin, antennae-like growths extending downward.

A structure similar to Necrozma's tail extends from the center of its back, and like its Dusk Mane form, can be used as a form of propulsion. There are eleven crystalline spikes attached around the body, four each on the wings, and three on Lunala's tail. These spines are capable of firing dark energy.

Dusk Mane Necrozma

Ultra Sun: This is its form while it is devouring the light of Solgaleo. It pounces on foes and then slashes them with the claws on its four limbs and back.

Ultra Moon: This is Necrozma’s form while it’s absorbing the power of Solgaleo, making it extremely ferocious and impossible to control.

Dusk Mane Necrozma resembles an armored Solgaleo with Necrozma as body armor. Dusk Mane Necrozma has armor around its paws, head, and sides. Necrozma's tail splits into two and attaches to the sides of Solgaleo's torso and its large claws extend from Solgaleo's back.

The front feet have five black claws attached to them with two V-shaped crystals on top of it while the back foot has only three claws. It has a triangular helmet with a long, thin antenna on each side and Necrozma's brain prism is prominently displayed. Solgaleo's own eyes and nose are visible as bright, blue lights.

The host's tail gains three black spikes attached to each other, as well as three spikes under the chin. A structure similar to one of Necrozma's legs extends from its back. Using the armor on its chest, it is able to propel itself by shooting black light.

Ultra Necrozma

Ultra Sun: This is its form when it has absorbed overwhelming light energy. It fires laser beams from all over its body.

Ultra Moon: The light pouring out from all over its body affects living things and nature, impacting them in various ways.

Ultra Necrozma is a colossal dragon mostly composed of pure light energy that it had stored from a great energy source, such as Solgaleo or Lunala, before its transformation. This body of light is supported by a sort of skeleton made from the various pieces of Necrozma's crystalline body; these pieces take on a golden glow from the light, but they return to black without it. Its sheer size makes it the tallest known Psychic-type Pokémon.

Its head is surrounded by several spikes and a pair of small wings, which causes it to resemble an eight-pointed star; there is also a small, lighter eight-pointed star on the back of its head. Its face is armored and has multicolored heterochromic eyes; the left eye is primarily red, while the right is mainly blue. The patterns around its eyes resemble an Ultranecrozium Z.

It has two pairs of wings: one around its shoulders and one around its hips. While the wings themselves are made of light, the arm portions are made of its former legs and shoulders, respectively. Its former arms now cover its lower legs, and what was once its tail covers its chest. Finally, it has a long tail with a row of spikes along the top.