All weapons
Press Left, Right, Up, Down at the title screen. Then hold Z and press Right, Right, Left, Left.
Easy Way to Destroy Bees
Here is an easy way to destroy bees: Wait to hear the buzzing sound that notifies you of their arrival. Then wait for them to get very, very close to you (when they lower their altitude to hit you). Use your weapon with star-type ammo to shoot them. You will hit them 99.9% of the time. If you shoot them and they hit you, you will not lose as much health as normal.
Infinite Lives
At the title screen press L, R, B, A, Z, Left, Right.
Level select
Hold Z and press Right, Down(2), Right at the title screen. Release Z, then press Right, Up, Down, Left, Left, Up, Right, Right.
All weapons...