Anywhere and anytime your in the game, you can get these two big missiles that cover the whole screen. When this happens, everything on the screen dies except you. I'm not sure how to get them but I have gotten them a couple of times bye dodging in patterns or shooting in patterns. These missiles are extremely rare and hard to get, but they're worth it.
Enter the passwords below to start at the corresponding level:
TY690-Starts last level with almost full power.
TY19U-Starts on the last level with maximum offense, defense, weapons, energy, and time.
Press and hold the B Button until you hear a whistle sound. Once you hear this, release the B Button for a very strong shot from your plane.