Reshiram is a white, bipedal Pokémon with draconic, avian, and mammalian traits. A long, voluminous wispy mane streams out from the upper side of the snout and outwards from its head. The top of this mane is adorned with two protrusions resembling ears. Reshiram's face is fringed with spiky features, and it has a small, pointed extension below the chin. Its eyes have blue irises and black pupils. There are two pairs of pointed teeth visible when its mouth is open, one in the upper jaw and one in the lower. Reshiram has a long and slender neck, with a fluffy, collar-like protrusion jutting out of two gray, glass-like neckbands. Its arms begin slender and arm-like but then flare into a more wing-like appearance, sporting four claws resembling hands on the leading edge. There are plates at the back of Reshiram's "hands" that sport a similar color to its neck rings. Reshiram has a feathered or furry feature on its chest, with the lower portion protruding outwards to a point. Long feather-like protrusions jut out of its thighs. On its feet are large gray claws, three at the front and one positioned at the back, resembling high heels. Reshiram's tail is a mass of plume and ribbon-like extensions, surrounded by two large bands, similar to the ones around its neck. When its emotions surge, it enters Overdrive mode, and its tail lights up with a fiery glow.
In Unovan legends, Reshiram and Zekrom were created from a single dragon Pokémon commanded by the twin heroes of Truth and Ideals when it split into two. Reshiram assists anyone who wants to create a world where the truth is valued, so it allied itself with the younger brother, whereas Zekrom sided with the younger brother, who sought ideals. The two dragon Pokémon battled each other, but were equally matched and unable to achieve victory, so the brothers ceased their conflict agreed that neither of them were right. However, their sons inherited their ideologies and resumed their clash; the Unova region was subsequently devastated by the combined might of the fire and lightning powers of Reshiram and Zekrom before the two Pokémon disappeared. Reshiram will transform into the Light Stone should its body get destroyed or when attacked by Kyurem's tendril-like appendages. It can willingly revert back to normal when awakened by a hero who believes in the truth.
When Reshiram's tail flares, it sends flames into the air which burn its surroundings and are hot enough to scorch the world. The heat energy from the flames rises into the atmosphere and changes the global weather. Zekrom and Reshiram activate each others' tail generators when they use an an enormous flame and an an enormous thunderbolt, respectively, at the same time, powering up both attacks. While flying, Reshiram spews flames from its tail as it soars through the sky like an airplane. Myth has it that Reshiram burns down the kingdoms of people who ignore the truth and become consumed by greed. In Pokémon the Movie: Black - Victini and Reshiram and White - Victini and Zekrom (M14), Reshiram is shown to be able to speak through telepathy. It loves Reshiram Treats made by Snacksworth, who once encountered it in the past.
(Source: Bulbapedia)
