Reshiram

Reshiram is a white Generation V Legendary Pokémon and the Version Mascot for Pokemon Black. It was first revealed on the official Pokémon website on May 28, 2010 along with Zekrom. It will not have a gender. It is one of the two main Legendary Pokémon, and will appear on the boxart of Pokémon Black. It is officially confirmed that it will have the Dragon type, and its second type is Fire. Reshiram also comes from the Japanese word "shiramu" which means to grow light. This may be a clue that means the two Legendary Pokémon, Reshiram and Zekrom, may have something to do with the sky. It is also rumored like in Pokémon Ruby and Sapphire there will be a catastrophic event that had occurred, and may occur once again between Zekrom and Reshiram making the sky very dark and very bright (respectively). Reshiram represents the Yang, which is light. With that information combined with the above, we can assume that Zekrom wishes to make everything night, while Reshiram wishes to make it daylight. It represents Yang which represents day and control.

Trivia

 * Reshiram's head and face look somewhat like a Suicune's head.
 * Reshiram and Zekrom are the only two Generation V Pokémon to have confirmed U.S. names at the same time as the Japanese ones.
 * Reshiram is the complete antithesis to Zekrom, having opposite colours (white and black),opposite postures (Reshiram faces right and has a low, horizontal stance while Zekrom faces left and has a high, vertical stance), but not opposite eye colours (red and blue are often thought of as opposites, but red's actual opposite is green, while blue's is orange).
 * Coincidentally, Reshiram is like the Blue-Eyes White Dragon from Yu-Gi-Oh and Zekrom is like the BEWD's antithesis, the Red-Eyes Black Dragon. However, their types are "switched", the BEWD's attack (in the English dub) is "White Lightning" while Reshiram is a -type and the REBD's attack is "Inferno Fire Blast" while Zekrom is an -type.
 * It was unveiled that Reshiram has higher Attack, Defense, and Speed than Zekrom.
 * Ironically, even though it is a Dragon type pokemon, Reshiram mostly resembles that of a Wyvern, due to the fact that Wyvern creatures have their forearms attached to the wings, while a true Dragon would have its wings separated from its arms.