To get 30 lives for Contra, use this code:
Up, Up, Down, Down, Left, Right Left, Right, Y, B
Begin a new game in Arcade Mode on Normal difficulty or higher, then as the first level begins quickly tap Up, Up, Down, Down, Left, Right, Left, Right on the DS touch screen, then press B, A, then finally tap the center of the touch screen.
This homage to the classic Konami Code must be entered before the helicopter drops you off at the start of the first level. Entering the code quickly and correctly will allow you start with 34 Lives.
Hold Y + B and press Start while the game logo is fading on the title screen to unlock the Sound Test menu in Super C.
To upgrade your weapons as far as they go, use this code:
Up, Up, Down, Down, Left, Right Left, Right, B, A, Start
This code will alternate between killing you, And granting you full power on a one-on, one-off basis. IE, If you use it, And it kills you, The next time you use it it will grant you powerups, Then kill you, then powerup and so on.
NES Contra - To unlock the nes contra beat 4 challenge mode missions and it is under the bonus content
Challenge Mode - To unlock challenge mode beat the game on any difficulty once
Super C - To unlock the Super C game beat 8 challenge mode missions and it will be under bonus content just like the nes contra
This glitch will give you 99 lives. You need to have 0 lives left and die at the same time you gain an extra live. You'll then have 99 lives.