How can you obtain the Knight Armor in Super Marios Bros 3?
This is perhaps one of gaming's longest held secrets, but dataminers have recently discovered there is a secret outfit mario can obtain, that has remained hidden until know.
In order to obtain the Knight Armor in Super Mario Bros 3, you must first defeat every level, optional on-map enemies, and open every toad house treasure from level 1-1, the way through to level 2-5 without picking up a single power-up, and without dying once.
One you have completed level 2-5, a new secret level will be unlocked. It will show up on the bottom-right of the map, where before there was a suspicious empty spot on the map before, and it will be labelled as level 6.
Go directly to level 6! Do not use a power-up on the world screen. If you stop over at any other levels or do anything other than go directly to the level, then 6 will disappear upon returning to the main map. When you get to level 6, you wil notice that it appears to be night (much like levels in World 8). Also, the surfaces are covered in ice (much like levels in World 6), and all the enemies you encounter are giant (much like levels in world 4). The screen will also be scrolling and you will have a much shorter amount of time on the clock. There are ZERO power-ups to pick up on this level. Once you get to the end of the scrolling, you will get to a pipe. Go down the pipe as soon as possible! With the shortened time clock, you will only have about 30 seconds to defeat the 3 enemies here. A hammer bro, a fire bro, and a boomerang bro.
If you manage to do this (good luck), a new toad house will open up to the north. Now you have a 1 in 3 chance of picking the correct box (and the location is randomized each time). If you select correctly, you get the Knight Suit! if you select wrong, you get a mushroom :(
What does the Knight Suit do? Honestly, for all that work, not a lot. It is most likely a reference to Arthur from Ghosts n' Goblins. You will move a little slower with the armor on, have a short-range attack with a sword,but if you get hit once, it goes flying off and you'll be back to normal mario.
There are easter eggs if you manage to defeat one of the Koopalings wearing it though!