Its body in its 50% Forme is shaped like the letter "Z" and appears to be a snake. It has a green top half and a black bottom with 5 Pillar-like shapes on its back. It has no arms or legs and has a various amount of scales on its body. Zygarde has two compound eyes and green shapes under them. It has a tail which is flat.
Zygarde Complete Forme has a large, humanoid body with a long tail similar to Zygarde 50% Forme's body. It has two similar appendages protruding from each of its shoulders. On each of these appendages is a hexagon and an undulating pattern; on its right side, these are colored blue, and on its left side they are colored red. It has multiple white protrusions on its body: three on each hand, one on each knee, and one and the front of its feet. Its torso is composed of a lower abdomen and an upper chest. The abdomen has a vertical, hexagonal pattern upon it with two thin, white, and vertical marks on either side. Upon the chest is thin, zig-zagging opening which fades between five colors: red, orange, white, cyan, and blue. The chest can open, revealing five cores of each color. Above this opening are two large green, hexagonal marks. Atop its chest is its crown-shaped head. It has three white hexagonal marks above four horizontal ones, the uppermost white one having a very thin diamond shape through it, and the lower two being eyes. Directly above the third mark is a final green hexagon. Surrounding the head are triangular protrusions connected by another upside-down triangle which is jagged at the top.
Zygarde 10% Forme has a relatively small, mostly black Dog-like body with a green "scarf" that continues beyond the neck. Its muzzle is black at the top and green elsewhere. Its eyes are white hexagons with a black outline and no discernable pupils; directly above the eyes are two small green hexagons which resemble eyebrows. On its forehead is a very thin, white ellipse. Its "scarf" is entirely green with a small hexagon connected to the bottom. This hexagon is either red or blue depending on which Core it is comprised of. On each of its legs are hexagonal protrusions, all the same color black as the legs themselves. On the front two legs, there are two. On the back legs are three protrusions, and on the left leg is a particularly long one made up of two hexagons. On each of its hind legs is another hexagonal shape, with a noticeable gap before a small square protrusion above it.
Zygarde Core is a part of the mind of Zygarde, and has a small and leafy-green gelatinous body comprised of a large, round head, a moderately-sized body, and a thin, hook-shaped bottom section which may be a tail. Its head is rounded except for a protruding, beak-shaped area at the bottom front which may be a nose or a mouth. Within its head is a single, oval eye which has a smaller black, oval pupil within it. Beside this eye is another white, semi-elliptic shape which may be a second eye. Within its midsection is a nearly regular hexagon. There are two known Zygarde Cores, one composed of a red hexagon and one composed of a blue hexagon. They are self-aware and can communicate via telepathy, monitoring the ecosystem around them. Zygarde Cores get their energy through photosynthesis.
Zygarde Cells make up Zygarde, and appears very similar to the Zygarde Core. Unlike the Core, it is flat, has a green pupil, and has a darker green, more elongated hexagon within its midsection. Unlike the Cores' hook-like bottom section, the Cells have a long and more noticeably tail-like back-end.
Zygarde is part of a legendary trio that include Xerneas and Yveltal, together spelling X, Y and Z, the last letters of the alphabet. They also happen to be the last Pokémon in the Mountain Kalos Pokédex.
Zygarde is the only Legendary Pokémon to have more than four formes.
Zygarde 50% Form is based off of a serpent in the form of the letter Z. Zygarde 10% Form is based off of a Doberman Pinscher on a green leash. Zygarde Cell and Zygarde Core are based off of cells and possibly planaria. Zygarde Complete Form is based on Hel, a Nordic goddess.
Zygarde's name has been derived from two words. "Z(ee)" responds to Z axis and "garde" is a French word meaning guard or protection. It is a part of Yggdrasil Trio.
Red Zygarde Core
Red Zygarde 10% Forme
Zygarde 50% Forme
Zygarde Complete Forme
Zygarde's 50% Forme as shown in the Pokémon Dream World