Start the game and enter the map mode. There, move the cursor on the letters' grid and press the A Button on certain characters to make passwords as below. (If you mix it up, just get off the letter grid and press A. If you want to enter multiple passwords, reset the console.) Press Start when you're done entering the password.

Effect	Password
DEBUG	Debug features unlocked.
OWARI	View ending.
SPEED	Greatly speeds up time.
YUSYO	"Famicom International Billfih Tournament 1988" instant win and ending.
ZANNEN	"Famicom International Billfih Tournament 1988" instant loss.