Change Character Names:

On the character select screen, press Select on the controller to go to a screen where you can change Alex and Ryan's names to whatever you want.

 

Kunio and Riki's Hidden Portraits (USA Version):

Start the game in Normal mode and enter the Status screen. Once in the status screen, hold Left on Controller 2 and press Right + Select on Controller 1. If done right, you'll arrive at a screen with a portrait for Kunio and Riki while the Double Dragon theme plays in the background.

 

Merlin's Mystery Shop:

To find Merlin's Mystery Shop go to the Armstrong Thru-Way. Once inside press up at the top wall and the wall will open. Inside you can buy the best items in the game.

 

Passwords:

 

Effect                                                                                                                    Password

Final Boss, w/ Max Stats, Dragon Feet, Stone Hands, Grand Slam,

and Texas Boots                                                                                                   XfMdZTHwiR3 jaj6jfRUDEt tilm2tWRo8b

Final Boss, w/ Max Stats, Stone Hands, Dragon Feet, Acro Circus,

Grand Slam, 4 Karma Jolts, and $999.99 cash                                              XfMdZTHUPR3 rztzPeQUCTt 61lxhtWRoZb

Ivan Beaten, High School Open                                                                     t1izvpdOZnZ JxNkJp7Cpub XMPQgXErSMF

Power Up

w412ysgtMqc MUSjKm2PqtE UJMNdUTGOQC

Start w/ all abilities and 500$ in cash                                                                      jrYplfTgbdj nOorLTIYXwR SjTuqpilUHP

Strange Item in Inventory that gives stat increases.                                   fHUFBbvcnpa MS8iPpICZJP VKNOeVRQPDD