New Super Mario bros Cheats: DS

[goodboys]

Cheat: Infinite Lives on World 4-5
To get infinite 1-UPs, you needn’t go any further than World 4-5. There, head to the first pipe spawning Bobombs. Clear a way to the lower (indestructible) floor, but leave the left and right edges in tact. Grab a Koopa Shell and toss it into the pitt, and then position yourself far away enough from the pipe so the Bobombs continue to respawn. If done correctly, the Koopa shell will bounce left and right endlessly, racking you up 99 lives in no time.

Cheat: World 8 (From World 5)
To get to World 8 from World 5, do the following. First, head to the house directly after the first castle on World 5. Once there, go up six flights of stairs. Next to the seventh flight of stairs, there will be three bricks. Jump on top of them and jump straight up to hit an invisible block. Then, get on top of that block, jump straight up again, and hit another block. This one will unleash a vine that you can climb up. Once atop the vine, there will be a door. Go through the door and get on the nearby colorful platform. The platform will bring you to another door. Go through that door and find the red flag with a skull on it (as opposed to a black flag). Jump on the flag so it comes down, thereby completing the stage. Then, go to the cannon it shows and you will be brought to World 8.

Unlockable: Play as Luigi
Beat the game and save it. Then, select the saved game and hold down both the L and R BUTTONS, then enter A. The green sporting super mario bro is unlocked.
I can confirm that you do not need to clear the game to play as Luigi. Just hold L + R and press A on the file you want to play, and you will be Luigi, regardless if you finish the game or not.

Unlockable: Special Backgrounds
First you beat the game. Then load the saved file for that game. Go into the blue Toad house now located in World 1. In here you can purchase five different backgrounds for your lower screen. They all cost Star Coins. To get the fift background, you have to get all of the star coins in the through-out all the levels.
Toady claims to get the fifth background you must collect all star coins. This is wrong. You only need to clear a path to every mushroom hut. Finish the game and a path to a blue mushroom hut will appear in World 1. It contains the starting touchscreen theme and three additional background patterns that can be purchased for 20 star coins each. A fifth theme can be bought once you've cleared paths to the mushroom huts in every world.