Metroid: Zero Mission Cheats

To open Time Attack Mode in which you get a password for your clear time and percent, choose a file that has the green+yellow Samus symbol and hit the A button. When you see the 'Start Game' option, simply hit Up, Left, Right, then Down on the d-pad and 'New Time Attack' will appear.

Normally, the final boss fight is pretty simple-it only takes 5 super missile hits to kill him, if you target the core.

However, if you achieve a 100% item collection rate, the boss will take 15 super missiles to kill, and will do 50% more damage, which varies with your difficulty level. So, if you have 100% on hard mode, the boss will take out three tanks with one swipe of his claw, instead of two.