To Play as Master & Uranus:
Press R1 L2 X L1 R2 0 on 1P controller on main title screen as the modes are appearing from each side. You should hear a "clink" & the logo will be blue.
The 'honest way':
To play as Master and Uranus you have to complete the 1-player mode at level 4. When the game starts over again go to random select and hold the select button until Master or Uranus appears then hit start.
To play as the hidden characters Vermillion and Sho you have to do the aforementioned with Master and Uranus, then play at difficulty level 5. Complete the game, start a new game and Vermillion and Sho appear on the random select.
To remove the Health Bar:
During a match pause the game then press and hold S, O, T, and X and then press Select twice.
Thanks to Revolution reader Thomas Gaboian!