Play as Bosses Japanese Version
Here's an easier way to get the bosses in the Japanese version. To get Uranus and Master: While the Options are flyng on to the Title screen, quickly press L1, L2, Triangle, R1, R2, Square. You should hear a fuuny tone if the code worked! To get Sho and Vermillion, do the same thing as the Uranus/Master Code except backwards (Square, R2, R1, Triangle, L2, L1) and use Controller Two. When the Character Select screen appears, hold Select to slow it down. The new characters will appear after Chaos.

Play as Vermilion or Sho
You'll have to earn these players too, but here's how.

Beat the game on level 6 in 1-player mode.

After the ending credits, look at the cursor on the main menu. If it's blue, you're in business.

Start a new game (any mode) and choose Random on the Character Select screen.

Hold Select to show down the character cycling. Uranus and Master should now be selectable.

Warp to Final Boss
To warp to the final boss, press Up, Down, Up, Down, Up + Triangle at the title screen.

Play as Uranus or Master
You'll have to earn these players, but here's how.

Beat the game on level 4 or higher in 1-player mode.
After the ending credits, look at the cursor on the main menu. If it's blue, you're in business.

Start a new game (any mode) and choose Random on the Character Select screen.

Hold Select to show down the character cycling. Uranus and Master should now be selectable.

Camera Tricks
On the Options menu, select control type "H2." Select "Camera Action" and scroll through the options until you see "Your Self." Select any of the control types and you'll see that the shoulder buttons (L and R) have now changed to camera controls. Begin a game and you'll be able to change the camera angles whenever you pause the game. Press Select while doing this to toggle between Rotate/Tilt and Zoom/Pan controls.

Extra Colors
Beat the game to add a little color to your life. To try on your new clothes, go to the Random select box and hold Select to slow down the cycling. When your character appears, press Weak Punch or Weak Kick to choose a new outfit.