Pikachu evolves when you give it a thunderstone.
NO!
If you transfer one yes. Pikachu are NOT wild Pokemon in Black and White.
pikachu is not in pokemon white you have to trade from another game.
You cannot find pikachu in pokemon black.
NO you can't get a pikachu on white (everyone has white what about black)
Yes, but you must trade it from a Generation IV or Generation III game to get one.
You can find Pikachu in the dreamworld, but not in the regular game.
You cannot find Pikachu in the wild in Pokémon White, the only options you have in regards to getting Pikachu in Pokémon White is trading for a Pikachu, trading for Pichu and evolve it, defeat the Elite 4 and receive the National Dex and then access the Poké Transfer in Route 15 in order to transfer a Pichu (Pikachu's pre-evolved form) or Pikachu over to Black or White from Diamond, Pearl, Platinum, HeartGold or SoulSilver or you would also have the option to transfer a Pikachu from the Dream World over to White once the Dream World goes online.
You will need to trade for it from Pokemon Black or White to get Pikachu. It cannot be found in the wild.
A Pokemon from another region. It can also mean a Pokemon from another version of the same game. (Japanese version) it's said that these Pokemon have a higher likelihood of shiny offspring, but i haven't been able to test it.
You can transfer your Dialga, Palkia, and Giratina to your Pokemon black or white version game (NOTE: ONCE YOU HAVE DECIDED TO TRANSFER THE POKEMON TO THE POKEMON TRANSFER LAB IN POKEMON BLACK OR WHITE VERSION, THE POKEMON THAT YOU SENT ARE UNABLE TO RETURN TO YOUR PREVIOUS GAME) or you may just use cheat codes on your AR to find any Pokemon that you desire whether it is a shiny Darkri to an average Pikachu. Have fun!
pikachu will not be in black and white unless you trade one or migrate it. if you watch the anime it will say that pikachu and other kanto/johto Pokemon are extremely rare in unova. shorten it there is a 1 in a million chance that a random A.I. trainer will have a pikachu.