In the very beginning of the game, right before the title screen,when you see the FMV of the dragon and all that stuff, press Up, Down, Left, Right, B, A. You should here a little chime to assure you that you did it right.
(supplied by: diginet387)
If your having a hard time beating Raditz, Vegeta, Nappa or Freiza and his troops do this. While flying get hit by an energy blast then stop flying. Now you are invincible unless you fly again then it goes away. But you can always do it again and it works on any villian.
At King Kai's planet you can hit Bubbles as many times as you want by going into King Kai's house right after you've caught Bubbles the first time and then you can chase him again.
There are 9 codes for this game.
Have All Attacks
Inf Flight Charges
Tons Of Items
Game Script, Final Version(Downloads are on an external site and open in a new window)
This FAQ is written in Dutch.(Downloads are on an external site and open in a new window)
FAQ/Walkthrough v1.3.(Downloads are on an external site and open in a new window)