When you fight the clown and Roo, defeat the clown first and Roo should hop away off the screen. When you lose all your lives and continue, cycle through the characters and Roo will now be available.
Ending 1
To get Ending 1, successfully rescue the Chief in Stage 6 before his health runs out. Then, at the end of Stage 7, defeat Robot Y before the time limit runs out. You will see the true ending.
Ending 2
To see Ending 2, manage to rescue the Chief before his health runs out in Stage 6. Then, in Stage 7, defeat Robot Y but let the time limit run out. You will see Ending 2.
Ending 3
To see Ending 3, let the Chief's health run out in Stage 6. When you go to Stage 7, you will see that it is changed. Make it to the last boss and defeat him. You will see Ending 3.
Ending 4
To see Ending 4 , simply set the difficulty on Easy Level and beat Robot X in Stage 5.
Extra Lives Select
Go to the options screen and select the ''Lives'' option. Press and hold UP + (A) + (B) + (C) on Controller 2, and press LEFT or RIGHT on Controller 1 to select the number of lives you can start the game with. You will now be able to select 9 lives, past the default max of 5.
Get Roo
At the title screen, hold Up and B, then press Start. A kangaroo named Roo will now be available at the character select screen.
Get Shiva
After beating Shiva in the first stage when you get the last hit, press B+Start and hold it. When the continue screen comes up you'll be able to play as Shiva. WARNING: He is weaker than his Streets of Rage 2 character.
Get Super Skate
Pick Skate. As the first level starts, lose a your first life having 0 points. You will now be Super Skate, with a much more powerful combo.
Land On Your Feet
While going through the many levels you will find that many enymies will through your character. If they do so then hold "up" and your jump button to land on your feet, and you will not get hurt!
No Damage From Falling
After being thrown by an enemy, it is possible to prevent taking damage from the fall by holding UP and the JUMP button while falling until you land. Your character should land on his/her feet and not take any damage at all. This is very helpful when fighting enemies like Signals and Ninjas.
Play as Ash (Japanese version only)
To select Ash, defeat him, then hold A on Controller 1. After losing all of your lives, you select to continue and you can choose Ash as your character.
Play as Super Axel
Press C to select a player, then quickly hold A and sweep the D-pad in a clockwise circle until Axel appears. Then press A. Note: This cheat is very hard to get working.
Play as Super Zan
On the Character Select screen, hold C button on both gamepads when selecting Zan and keep holding them until the game start. You will have Super Zan afterward.
Play as the same character
Hold Down+C on controller 2 as you enter 2 PLAYER mode with controller 1.
Shiva's infinite combo
When playing as Shiva, you can hit the opponent over and over again until they die without them being able to escape you by pressing Z on a 6 button pad or B and C together on a 3 button one over and over again. This will work on any opponent apart from the ones that can block and the bosses (excluding Jet)