Super Mario 64 DS

Super Mario 64 DS is a three-dimensional platformer launch title and remake of the original Super Mario 64 for the Nintendo DS, most notable for adding minigames, 3 new playable characters, 30 extra power stars (150), new levels, and improved graphics. It's regarded to be one of the best games for the DS, Selling 11.06 million copies worldwide.

Similar to the Nintendo 64 version, the game starts with one of the 4 protagonists, Mario getting a letter from Princess Toadstool inviting him to her castle for cake. Arriving with his brother, Luigi and arch-rival, Wario they head to the castle and enter it. The crew split up and enter different painting worlds to then be captured and trapped in the walls by their archenemy, Bowser. After a long period of time has passed, Lakitu wakes up Yoshi to inform him that Mario hasn't returned yet. From then on, Yoshi must unlock the castle and journey to save Mario, Wario, Luigi, and Princess Toadstool by entering the many paintings that lead Mario and his crew to levels so they can collect as many stars as possible, while freeing Toads from the castle walls.

Cut Concepts
Some cut concepts and ideas from the original Super Mario 64 such as Luigi and Yoshi being playable made it back into Super Mario 64 DS, most of which were thought of in 1995-1996.

Earliest builds
A demo of one of the earliest known builds of the game was playable at E3 2004. In this demo players would choose from a menu on the touch screen where they could choose different painting worlds, most of which seem to contain a different picture from the final game. Another menu for multiplayer where you could choose between the 4 could appear upon starting the DS. In single player, the touch screen allowed for switching between the 4 characters as opposed to entering different character rooms in the final game.

Showcased at the same E3 was another demo titled "Mario's face", where the player could use a stylus to stretch Mario and Wario's face, and even make it 3D or outlined like a cartoon. This build is clearly what ended up being Mario's face in the title screen of the game.

Phenomena
Discovered and theorized recently, every copy of Super Mario 64 is personalized. Nintendo implemented an experimental procedure into Super Mario 64 which slightly alters the game to suit the player whose playing it, which is why some players report that there's always something off when playing somebody else's copy of Super Mario 64. This can also reportedly include Super Mario 64 DS, as there are many reports of the game having anomalies such as new levels or even a new character.

Waluigi
Upon its release, Waluigi was highly speculated to be playable in Super Mario 64 DS, finishing the set of 4 plumbers in-game. The fourth key door outside the Rec Room was the likely source of this belief, although all it contains is a star, and when entered after gaining the star will scare off the player with the laughter of Boos. This can be unlocked with the key obtained by catching all the shiny white rabbits. Despite that, many still believed that Waluigi was intended to be in the game and his existence has acted as Super Mario 64 DS' most talked about rumor.

Several rumors and images were created around Waluigi, most famously the Purple Prizes rumor. This newsletter claimed that Waluigi could be found by being the "fastest foot-racer in the land" and defeating the secret "Rabbit king", and only then will Waluigi be playable. However, this was an April Fools joke orchestrated by DeviantART user King-Bowser-Koopa, though it matches up fairly well to the Rabbit Meadow level, meaning it may have been based off of a personalized copy.

Wow! Waluigi & Starpass
Main Articles: Wow! Waluigi & StarPass

Super Mario 64 DS was initially planned to be released alongside a cancelled game, known as Wow! Waluigi. This game had Waluigi star as the main protagonist for the first time ever. It was planned to be linked to Super Mario 64 DS via the similarly cancelled StarPass application that would allow 2 games to be linked, which would unlock Waluigi in Super Mario 64 DS, and a new level and playable character in Wow! Waluigi. However, Wow! Waluigi and the StarPass were cancelled when it was discovered the Personalization A.I. somehow spreads through the StarPass to games linked with SM64DS, making them incredibly unstable and potentially unplayable due to them not being made for the A.I. This resulted in StarPass' cancellation, and alongside it, Wow! Waluigi, as the game no longer had a purpose. However, Waluigi can still reportedly be unlocked in Super Mario 64 DS, as the A.I. can bring back the data related to him in some manner, circumventing the StarPass in the first place.

Trivia

 * With some personalized copies of Super Mario 64 featuring Luigi or even Wario as playable characters, as well as other anomalies such as the Submerged Castle and Bowser's Chamber, it's possible that Super Mario 64 DS is based off of a heavily personalized version of the original Nintendo 64 game.
 * Super Mario 64 DS isn't exactly the original Super Mario 64, so it is possible that the DS version can't be personalized.