Yay
Well, actually, there's some serious luck involved.
Flying and Surfing Pikachu are Class A Pokemon, and they only appear 2-3% of the time, respectively. When you use the Pokeradar, a triple exclamation mark bubble denotes a Class A Pokemon will appear. (So when the bubble appears above the grass to tell you to pick there, (!) means a Class C, (!!) means a Class B, and (!!!) means a Class C, which is what you want, what you find is based on luck) Also, when you first take your Pokemon for a walk, the Pokewalker chooses 1 Pokemon from the 2 possible for each Class, so you can only get
either a Flying
or a Surfing Pikachu per walk.
Goes untill may 5th, Dummy
The Spiky-Eared Pichu event is over