Yes, yes you do. Only people with a legal copy of HG and SS will be able to partake in this due to it containing the pokéwalker. The pikachu are found during a course the game unlocks when you use mystery gift on wifi.
I must have horrible luck then. I have caught 18 pikachu, and every single one of these suckers are male. *pokes them* Nothing rare yet either.
Damn ah well just gona have to look for a trade or settle for a regular pikachu. Thanks