* Play as Dio : At the character select screen do the following to make Dio appear...
highlight Alessy and press START
highlight D'Bo and press START
highlight Chaca and press START
highlight Milder and press START (x3)

* Play as Shadow Dio : At the character select screen do the following to make Shadow Dio appear...
highlight Alessy and press START
highlight D'Bo and press START
highlight Chaca and press START
highlight Milder and press START (x3)
highlight Dio and press START (x10)

* Play as Young Joseph : Enter the following at the character select for Young Joseph...
highlight Jotaro and press START
highlight Polnareff and press START
highlight Joseph and press START
highlight Kakyoin and press START
highlight Iggi and press START
highlight Avdol and press START
highlight joseph and press & hold START until Young Joseph appears.

* Unlock time release characters : To unlock the time release characters all at once, you need access to the machine's test menu. From there, go to Configuration, then Game, and enter the following code. A sound will confirm it. P1 Up, Down, Right, Left, Button 1, Button 2, Button 3, Button 4. If you hear Dio's 'Wryyyyyy', it was successful. Proceed to 'Save and Exit', and the new playable characters will be available on the opposite sides of the character selection screen. They consist of : Shadow Dio, Kahn, New Kakyoin, Hol Horse with Boingo, Rubber Soul, and Young Joseph.

* Developer Mode: In order to access the hidden developer menu, the second byte of the arcade game's region value needs to be set to "7". Once done, the following options are available:
Pressing button 5 during gameplay will pause the gameplay until it is pressed again.
Pressing button 6 during gameplay will slow the game down. Pressing it while paused from button five will act as a frame advance.
Holding button 1 while activating the service menu will open a developer's test menu.