R-Types Cheats (PlayStation)

Press L2 ten times and R2 ten times at either the R-Type or R-Type II option at the title
screen. Press Start while playing 
  to access any level or view the FMV sequences.

Repeatedly press Select at the title screen of any R-Type game to get up to 99 credits.
This may also be done at the countdown on the game over screen to continue.

Pause the game then hold L2 and press Right, Up, Right, Up, Down, Left, Down, Left, X.

Pause the game then hold L2 and press Right, Up, Right, Up, Down, Left, Down, Left,
Circle.

Press Start to pause game play in R-Type or R-Type II. Hold L2 and press Right, Up, Left,
Right, Down, Left, Up, Right followed by one of the following buttons for various weapons:
Triangle, Square, X, Circle, or R1.