Xerneas is a quadrupedal, stag-like Pokémon with four pairs of antlers. Its appearance changes slightly depending on whether it is in Active Mode or Neutral Mode. Regardless of its mode, its primary body color remains black, featuring a blue stripe along its back and a short, bushy tail. Starting from its knees, each leg has a blade-like trim that forms a point beneath each hoof. There's an upside-down V-shaped marking on its chest, matching the color of the leg trims. Its head and neck are blue, adorned with two large tufts extending onto its chest and curving upwards. The first pair of antlers extends onto its head, curving around the underside of its eyes. Xerneas' eyes are black with X-shaped pupils, and it has a short marking atop its snout and upward-curving horns on either side of its head instead of ears.
In Active Mode, Xerneas' markings, antlers, and leg trims turn pale gold. Its antlers feature branches and bumps in various colors, and there are multicolored spots on its back. In Neutral Mode, these elements appear pale blue, with darker blue embellishments on the antlers and spots on its back.
Xerneas possesses the power to bestow eternal life, activated when the horns on its head shine in seven colors. As depicted in "Diancie and the Cocoon of Destruction," if Xerneas expends too much life energy, it transforms into a tree and sleeps for 1,000 years. It can revive those petrified by Yveltal, though as shown in "The Legend of X, Y, and Z!," this isn't always possible.
A unique Xerneas is revered in Lental as one of the seven guardian Illumina Pokémon, celebrated for saving the region from a meteorite. It resides at the Aurus Island Illumina Spot.
Forms
Xerneas has two forms: Active Mode and Neutral Mode.
(Source: Bulbapedia)










