transfer from diamond pearl platinum HG SS
You can find Pikachu in the dreamworld, but not in the regular game.
You Can't Get Pikachu in Black or White but you can trade from another ds or wii and get pikachu. You can see a pikachu though, if you go to Castelia City and go to the road that leads to Route 4, if you go into the building to the left, there is a PIKACHU! XD
You will need to trade for it from Pokemon Black or White to get Pikachu. It cannot be found in the wild.
So far, in Japan, he has Pikachu, Oshawott, Tepig, Tranquill, Snivy, Scraggy, and Swadloon. In the USA he has Pikachu, Oshawott, Tepig, Snivy, and Pidove.
You cannot find Pikachu during normal gameplay in Black/White. Sorry!