Reshiram is a large, white, Dragon-like Pokémon that seems to share its theme with its counterpart, Zekrom. It has a face that slightly resembles that of a white lion, striking blue eyes, and several silvery-white rings around its thin, swan-like neck and flowing tail, with a single band around each of its hands. It also has feather-like arms that end in four claws and a flowing white mane. Its chest feathers resemble the design of the Silver Wing. The lower portion of its body protrudes outward to a point.
It's revealed in Black and White 2 that Kyurem, along with Zekrom and Reshiram were all part of a single Pokémon.
Reshiram is the only known Pokémon with a permanent Fire and Dragon typing. The only other Pokémon with this typing is Mega Charizard X.
Reshiram's name appears to have originated from the Japanese word "shiro" which means "white", referencing its color.
Reshiram, along with Zekrom and Kyurem is part of the Tao Trio. Reshiram embodies dynamism.
Reshiram is the only known FirePokémon that is not weak to Water.
In Movie 14, Reshiram has the same roar as the monster Megaguirus, from the Godzilla franchise. Originally, this roar was Zekrom's, but for Movie 14, Zekrom was given the roar of Baragon, also from the Godzilla franchise. Megaguirus' roar had previously been used in Movie 11 when Zero's fighter released an attack.
Reshiram also appears in a Dream World minigame; if the WIFI Reshiram from the White version game is sent to the Dream World, in the special home Victini appears to the player, and in the minigame's intro, Victini fails to destroy the barrier alone, so the player must ask his/her WIFI Reshiram to help destroy the barrier by collecting power ups, and at the end, Reshiram destroys the barrier by using a flame attack.
It protects the PokéPark in PokéPark 2 while Zekrom protects Wish Park.
In Hyperdimension Neptunia, a DLC weapon for Ram, the Staff of Ideals, is based on Reshiram when fused with Kyurem.