Codes:
Hold A + B on the gameover screen, then press start. - (SMB1) Restart after game over

On the title screen, press A, B, L, and R all at the same time. - (SMB1) High Score Reset

On the title screen, press A, B, L, and R all at the same time. - (SMB:LL) High Score Reset

Pause then hold L+R and press select. - (SMB2) Kill Yourself

Unlockables:
Complete the first 8 worlds without warping. - (SMB:LL) World 9

(SMB 3) Hidden White Mushroom Houses:
In certain levels, the screen moves forward and pushes you along. If you get a certain number of coins within these said levels, you unlock a secret white mushroom house holding a powerful item. Below are the levels and the number of coins needed in each level.

White mushroom house: Level 1-4 Collect 44 coins within the level
White mushroom house: Level 2-2 Collect 30 coins within the level
White mushroom house: Level 3-8 Collect 41 coins within the level
White mushroom house: Level 4-2 Collect 22 coins within the level
White mushroom house: Level 5-5 Collect 28 coins within the level
White mushroom house: Level 6-7 Collect 78 coins within the level
White mushroom house: Level 7-2 Collect 41 coins within the level

(SMB1) Warp Zone to Level 2, 3, and 4:
To find a Warp Zone that can take you Level 2, 3, or 4 go to the part of world 1-2 then get to the part of the world at the end where all the platforms are moving up. Jump on one, then leap on top of the ceiling from there. Keep going until you reach five pipes. It'll say ''Welcome to Warp Zone!'' with a number above each pipe. The 2 takes you to level 2, the three to level 3, and the four to level four.

(SMB1) Warp to world 5:
Get on top of the ceiling in world 4-2 and run past the end pipe that leads to the flagpole. You will find a lone pipe that warps you to world 5

(SMB1) Warp Zone to Levels 6,7,and 8:
Go to world 4-2 Go past the first set of down platforms to 3 seemingly unreachable blocks. Uncover 2 invisible blocks under the rightmost and center bricks by jumping. Hit the left brick to sprout a vine. Climb the vine up and proceed right. You will find Warp zones 6,7, and 8

(SMB2) Warp to World 4-1:
Go to world 1-3 and find a potion. Now find the vase next to the brick building all the way to the right side of the level. Drop the potion and go into Sub-Space Warp into the vaseby standing on top of it and pressing Down on the d-pad. You will warp to World 4.

(SMB2) Warp to World 5-1:
Go to World 3-1 and enter the door to the waterfall and clouds. Drop down the waterfall to a door way down below. Find the potion in the huge patch of vegetables and take it to the vase next to the door. Enter Sub Space and stand on top of the vase and press down on the d-pad to enter the vase. You will be taken to 5-1

(SMB2) Warp to World 6-1:
Go to World 4-2 and proceed to the whales. Find a potion and get to the island with the vase. Place the potion down and enter the door that appears to go into Sub Space. Warp down the vase to World 6-1

(SMB2) Warp to World 7-1:
Go to World 5-3 and find a potion. Proceed all the way back left and use Luigi's squat jump or an enemy to get to the platform with the vase. Drop the potion and enter Sub Space and warp down the vase to World 7-1 (SMB3)

Warp to Level 8:
Get the first 2 warp whistles (Find a white block and crouch on it for 5 seconds in 1-3, then proceed right to the goal)

2:Enter the World 1 Fortress and reach the first door with Raccoon power (you should see a Dry Bones and a ''?'' block. Now step on Dry Bones and get enough speed to power your flying meter and fly over the level (Lots of A tapping) then proceed all the way right on the ceiling, and press Up on the d-pad to enter the door and get the chest. Now use the first Warp Whistle on the map screen to warp to the warp zone. Then while still in the warp zone (without warping) use the 2nd whistle. It will send you to the isolated World 8 Pipe. Using a warp whistle to get to the warp zone then using another whistle in the warp zone itself takes you to level 8 no matter where you are. You can also reach World 8 by using the warp whistle in World 7 once.

(SMB1) Fireworks:
If you finish a level (touch the flagpole) when the ones digit of the time is 1, 3, or 6, there will be that many fireworks and each one is worth 500 points.

(SMB2) Warp to World 4-1:
Take a potion to the isolated vase to the right of the door into the building in 1-3. Place the potion close to the vase and go through the door to Sub Space. Stand on top of the vase while in Sub Space and press Down on the d-pad to warp to World 4-1

Worlds A, B, C, and D (Lost Levels):
In Super Mario Brothers: Lost Levels, if you complete the game without warping, (Going through worlds 1-8, AND world 9), then you will move on to 4 secret special worlds. Worlds A, B, C, and D.

SMB & Lost Levels - 5000 points from Timer:
Make sure you're Fire Mario/Luigi when you reach Bowser. Blast him with fireballs, but don't grab the axe just yet. Instead, wait the timer out, but make sure you're next to the axe when there's about 50 seconds left. Now get ready and time your jump on the axe so the Timer reads '000'. Once you reach Toad and the game adds the Timer to your score, you may notice that it changed from '000' to '999'. Thus the game thinks you finished with '1000' on the Timer and times that by 5. Note: this does not work on the Original NES version of the game.

Infinite items in Super Mario Bros 3:
Complete levels until you get to toad’s mushroom house, where you get to open a chest for an item. Get the item, save and exit. Now reload the file and the levels you finished will still be completed but toads house will be back so you can get the item again! :D Repeat until you have as many as you need. Also this works for the extra lives slot and the memory card game houses too.

Harmless Bowser (SMB3):
At the end of the game, when Bowser uses his jump attack on you, duck if you are big Mario, or stay still if you are small Mario. Bowser will break the bricks, but he won't hurt you. If you are small Mario, you can run right through Bowser and not get hurt. In other words, Bowser's lower half is harmless, but his upper half can still hurt you.

(SM:LL) Extra Life at the flagpole:
To get an Extra Life, make sure that when you touch the flagpole, the last digit of the timer is a multiple of the number of coins you have (Example: TIMER = 231/COINS = 11). This also works with 0. Do this correctly and instead of getting a point bonus, you will get a 1-UP.

'Hide' behind scenery (Super Mario Brothers 3):
To ''hide'' behind scenery, simply hold down for a couple seconds while standing on a white block. Then your player can ''hide'' behind scenery for about thirty seconds.

28 P-Wings (Super Mario Brothers 3):
Complete the game and watch the ending. Now start a new game. You will start at World 1 with 28 P-Wings.

Morph a wandering hammer brother into a treasure ship. (Super Mario Brothers 3):
To turn a wandering hammer brother (the ones that walk about on the world map) into a white ship full of coins, collect a number of coins that is a multiple of 11. Make the tens digit in your score match the multiple of 11. Stop the timer at the end of the stage that you are playing in on an even number. One combination would be: 11 coins, 9,310 as your score, and the timer at 104. This only works in worlds 1, 3, 5, and 6. To get the N-Spade Card Game (Super Mario Brothers 3)

To get the N-Spade card game to appear on the World Map:
You must do gain 80,000 points as one player, and successfully beat the stage that you broke the 80,000 points with.

Warp Whistles (Super Mario Brothers 3):
Level 1-3 Find the white block near the end and crouch on to of it for 5 seconds. Then proceed to the goal, and go behind it. You will find a Mushroom house with a Whistle.

Level 1 Fortress Fly over the top of the level when you find the first door with your raccoon powers, and find a hidden door at the far right on the ceiling. It leads to a warp whistle

Level 2 Hammer Brother Get the Hammer from one of the Hammer Brothers here and use it to destroy the rock at the upper right corner of the Level 2 Map. Then engage the hammer brother on the other side. You should get a chest with a Warp Whistle.

Warp Zone (Super Mario Brothers):
To warp to Worlds 2, 3,or 4 during World 1-2, go to the end where the 2 platforms are rising, get on the first platform, and use it to jump onto the highest structure in the middle, then jump on the next rising platform, but this time, when it reaches the top, jump onto the TOP of the level. Walk foward and drop down the small jump, and you can now warp to Worlds 2, 3, or 4 by going down the desired tube, and pressing down.

To warp to World 6,7 or 8 during World 4-2, go to the place where three blocks are can be seen (where a pipe can also be seen). Jump below the third block where you can reveal a secret block but be careful on jumping below the 1st block because you can't break it thus going to the secret warp world unless you are a small Mario. Then step on to it and break the 2nd and the 3rd block. After you have done this, go down, then jump again below the second block now (it should have been broken now). The position of the two revealed blocks must be a stair from right to left. Anyway, step on to the 2nd block then braek the 1st block and there you can see the vine going up. Climb until you reach the day light again. Get some coins if you wish and you can now see three pipes like in the secret warp Worlds 2,3 and 4. Go down your desired pipe.

At the very end place of world 4-2 (where you can see the pipe going to the flag) jump on the long pipe and break the brick above it and go through the end and you can see the pipe going to the World 5.