Hold Select while you are choosing your team and opponents. When you start, you will be pitching.
Sound Test
On the Mode Select screen, press Select until either "Edit Team II," Set Up," or "Watch" modes are lit up. Hold the L and R Buttons, then press Start to access the sound test screen. Press any direction to change the number, and press B to listen to the desired music.
Speed Mode
When you are choosing your team, while holding the L and R Buttons, press Start to begin the game. This trick will more than double the speed of the players on both sides.