When you defeat the Elite Four, there will bw a Team Plasma confrontation (Trying to avoid spoilers) and Reshiram will be revived.
go to N's castle and use it to revive reshiram before your final battle w/ N.
dito evolves into reshiram
You don't find Reshiram in Pokemon White. You can only get Reshiram in Black.
reshiram does not evolve
No, Ash does not capture Reshiram.
No. Reshiram is a Black only Pokemon.
No, you cannot make a Reshiram Egg.
no ditto and reshiram both do not have genders
Reshiram is not in pokemon white, Reshiram is in pokemon black however you can trade Reshiram over to white. Instead of Reshiram you get Zekrom near end game
Reviving Reshiram from the Light Stone is only possible in "Pokémon Black" and this happens automatically after you have defeated the Elite 4 and went to N's Castle in order to confront N there. Why does everyone ask before they try anything?
Reshiram is genderless, but is designed to be like a female.
Reshiram is not in White. You can only find it in Black.