Guilty Gear cheats and cheat codes for Playstation

Unlock Hard mode
Hold Down + Square + L1 + R2 and the power button on the PSX. 
Keep the buttons held until the phrase "Team Neo Blood" disappears. 
If the code is accepted, the "Normal Mode" will change to "Hard Mode" 
and "Hard" will appear above the two chaos bar.

Unlock bosses: Testament, Justice, and Baiken (Japanese version)
Hold Down + Square + L1 + R2 buttons at the Arc System Works logo. 
Then, release those buttons, when the message "Team Neo Blood" 
disappears. Now you can play as the bosses in versus mode.

Change colors
Press Square, Triangle, Circle, or X at the character selection screen. 

Guilty Gear Game Shark Codes:

Characters for Player 2
8013904C 0000 - Potemkin                                          
8013904C 0001 - Zato-1                                            
8013904C 0002 - Sol-Badguy                                        
8013904C 0003 - Ky Kiske                                          
8013904C 0004 - Chipp Zanuee                                      
8013904C 0005 - May                                               
8013904C 0006 - Axl Low                                           
8013904C 0007 - Millia Rage                                       
8013904C 0008 - Kliff Undersn                                     
8013904C 0009 - Dr.Baldhead                                       
8013904C 000A - Testament                                         
8013904C 000B - Justice                                           
8013904C 000C - Baiken                                            

Character for player 1
80139048 0000 - Potemkin                                          
80139048 0001 - Zato-1                                            
80139048 0002 - Sol-Badguy                                        
80139048 0003 - Ky Kiske                                          
80139048 0004 - Chipp Zanuee                                      
80139048 0005 - May                                               
80139048 0006 - Axl Low                                           
80139048 0007 - Millia Rage                                       
80139048 0008 - Kliff Undersn                                     
80139048 0009 - Dr.Baldhead                                       
80139048 000A - Testament                                         
80139048 000B - Justice                                           
80139048 000C - Baiken                                            
  
Unlimited Time                                         
8007BF72 0000
  
Unlimited Health for player 2                                    
8007CB68 00BC
  
Full Power for player 2                                          
8007CB88 0040

Unlimited Health for player 1                                    
8007CB98 00BC
  
Full Power for player 1                                          
8007C8B8 0040