SMBX cheat codes

note : cheating in SMBX will disable your saving game.
In order to activate these codes, you have to type them in while playing a world or playing a level:

Player cloning cheats
These cheat codes either clone the player or get rid of existing clones.

supermario2 - Mario and Luigi appear and the level becomes 2-player: to switch the two press Down and the Drop Item button together.
supermario4 - Clones player 4 times.
supermario8 - Clones player 8 times.
supermario16 - Clones player 16 times.
supermario32 - Clones player 32 times.
supermario64 - Clones player 64 times.
supermario128 - Clones player 128 times.
1player - Gets rid of all cloned players, leaving with just the one player.
2player - Same as supermario2; makes the level 2-player.

Player character cheats
If you are playing as somebody else, these cheat codes change the player character to another character.

itsamemario - Turns the player into Mario if the player is somebody else.
itsameluigi - Turns the player into Luigi if the player is somebody else.
ibakedacakeforyou - Turns the player into Peach if the player is somebody else.
anothercastle - Turns the player into Toad if the player is somebody else.
iamerror - Turns the player into Link if the player is somebody else.

Item stock cheats
These cheat codes spawn an item in the item stock.

needashell - Reserve box holds an SMW green shell.
needaredshell - Reserve box holds an SMW red shell.
needablueshell - Reserve box holds an SMW blue shell.
needayellowshell - Reserve box holds an SMW yellow shell.
needaturnip - Reserve box holds a turnip.
needa1up - Reserve box holds a 1-Up.
needamushroom - Reserve box holds an SMB3 Mushroom.
needaflower - Reserve box holds an SMB3 Fire Flower.
needaniceflower - Reserve box holds an SMB3 Ice Flower.
needaleaf - Reserve box holds a Super Leaf.
needatanookisuit - Reserve box holds a Tanooki Suit.
needahammersuit - Reserve box holds a Hammer Suit.
needaclock - Reserve box holds an SMB3 Stopwatch.
needanegg - Reserve box holds an egg that contains nothing.
needaplant - Reserve box holds a Piranha Pipe.
needagun - Reserve box holds a Billy Gun.
needaswitch - Reserve box holds a P-Switch.
needabomb - Reserve box holds an SMB2 Bomb.
needashoe - Reserve box holds a Kuribo's Shoe.
needaredshoe - Reserve box holds a Podoboo's Shoe.
needablueshoe - Reserve box holds a Lakitu's Shoe.

Item hold cheats
These cheat codes spawn an item into the player's hands for use in the level.

firemissiles - Player holds a Billy Gun.
boingyboing - Player holds a Springboard.
wherearemycarkeys - Spawns a key in your hands to use in a keyhole.
hammerinmypants - Player holds a Hammer Bro. and can throw hammers.
powhammer - Player holds a POW Block.
bombsaway - Player holds an SMB2 Bomb.
rainbowrider - Player holds a rideable Rainbow Shell.
upandout - Player holds a Propeller Block.
burnthehousedown - Player holds a Propeller Flamethrower Block.

Yoshi egg cheats
These cheat codes spawn the Yoshi Egg in question into the player's hands.

greenegg - Player holds an egg containing a Green Yoshi.
blueegg - Player holds an egg containing a Blue Yoshi.
yellowegg - Player holds an egg containing a Yellow Yoshi.
redegg - Player holds an egg containg a Red Yoshi.
blackegg - Player holds an egg containing a Black Yoshi.
purpleegg - Player holds an egg containing a Purple Yoshi.
pinkegg - Player holds an egg containing a Pink Yoshi.
coldegg - Player holds an egg containing an Ice Yoshi.

Level-testing cheats
These cheats are useful for more extensive level testing.

shadowstar - Turns the player character into a darker version and lets the player walk through walls.
moneytree - Player will get coins really fast, and get a 1-Up every second.
ahippinandahoppin - Allows unrestricted jumping.
stophittingme - Damages the player. Useful if you want to turn off the "donthurtme" cheat temporarily without disabling it.
wingman - All flight-based power-ups (Super Leaf, Tanooki Suit, Fairy, Gold Link, Yoshi with Blue Shell, Blue Yoshi with any shell) work like P-Wings; they allow infinite flight.
sonicstooslow - Makes the player run faster.
......

Spoiler:

istillplaywithlegos - Resets all tiles in the level.

Settings cheats
Enabling these cheat codes is the same as enabling the respective setting in the level editor:

stickyfingers - Same as "Grab All" in the editor: allows the player to grab any object in the level.
donthurtme - Same as "God Mode" in the editor: makes the player immortal.
framerate - Same as "Show FPS" in the editor: shows the FPS of the screen.
speeddemon - Same as "Max FPS" in the editor: everything happens at the highest FPS possible.

World map cheats
These cheats only work in the world map.

imtiredofallthiswalking - Enables all levels in the world map.
illparkwhereiwant/iparkwhereiwant - Allows unrestricted movement across the world map.

Misc. cheats
These cheats don't fall under any category.

wariotime - Turns all enemies on the screen into coins.
iceage - Freezes all enemies on the screen.
captainn - Pressing the Pause key stops time like a Stopwatch (does not work if Pause key is Esc.).
flamethrower - If the player has a Fire Flower/Ice Flower/Hammer Suit, pressing the Run button allows autofire of fireballs/ice balls/hammers.
fairymagic - Turns the player into a fairy.
itsrainingmen - 1-Ups rain.
donttypethis - Makes SMB2 Bombs rain. They will explode upon hitting the ground.
wetwater - Changes the background and music to SMB3 Underwater, and enables "Underwater" mode.