This are the beta elements of New Super Mario Bros. D.I.Y., which are elements of the game that didn't make it into the final version.
Originally the game for going to include characters from other series including Sonic, Kirby, and even Link were planned to be playable in the game but were cut because EEA Inc. wanted a classic Mario cast. When the game was in early development, before it was even announced, we wanted more unique characters to grab everyone's attention. However, we knew that it would work out better in the long run if those characters weren't in the game. It would have been cool, but it just wouldn't work., says EEA Inc. EEA Inc. also had the idea of making the game just about Toads, having a game featuring playable red, blue, yellow, green, and purple Toads in a 2D platformer. The features for the game were not even confirmed yet. Yes, the game was going to feature just Toads, but with the new D.I.Y. format, the players can just customize their own Toads, so it would just be better to keep the Mario Bros. as well. Also, Toadette and Goombella were going to be playable in the game, but were taken out for unknown reasons.
Items & Power-Ups
In early development, EEA Inc. was viewing the unfinished game, New Super Mario Bros. Omega. The game featured many unique power-ups including the Burning Mushroom, Frozen Mushroom, and Phoenix Suit. EEA Inc. was going to feature them all but soon discovered that the game needed more old stuff than new for the time being. Despite that, EEA Inc. chose to include their new item the Bowser Mushroom to replace the Phoenix Suit. New Super Mario Bros. Omega is popular and has to stay popular. Stealing all their ideas just wouldn't be right and it would just be a plain rip-off., says EEA Inc.
The Whomp King from Super Mario 64 and Super Mario Galaxy 2 was going to be a boss. He was even in late trailers, confirming his appearance, but for unknown reasons, EEA Inc. replaced him with a beta boss in the original New Super Mario Bros. called Mega Whomp. EEA Inc. also thought about putting Big Bob-omb in the game, but came to a conclusion and included Big Mr. I instead.