Go to a fence that you can jump over and jump over it then turn and talk to Pikachu it will do a little dance for you!

Make Pikachu Wear a Bucket on Its Head

This only works for yellow version. Go to a spot that you can fish any spot will work. Make Pikachu stand next to the water as you fish. Fish using any rod. Then once your done fishing turn and talk to Pikachu he will be playing around with a bucket on its head.