When Pikachu apears on the menu screen when running to you, make single player and multiplayer pop up, then drag Pikachu to tease him.
Control victory screen
After winning a cup, use the touch screen to drag Pikachu.
Extra Tracks
Upload a Pokemon from a "Game Boy Advance Pokemon" game to unlock a new track. Each individual Pokemon will create a new track.
Hard GP Tracks
Win the GP to unlock a hard version of it.
Play With Pikachu's Body
When you win a cup, you can play with pikachu's body by clicking and dragging parts of his body.
Shiny trophies
Win a cup without retrying any of its races.
Speed Up Credits
When the credits are rolling, use the Touch Screen to scroll down faster to speed past the credits. After the credits roll it tells you in total how far you have dashed during the game.