Gold Mini Mario
From the Super Mario Wiki
Mario vs. Donkey Kong 2: March of the Minis
In Mario vs. Donkey Kong 2: March of the Minis, they are the same as their normal counterparts; however, if the player finishes a level with a Gold Mini Mario at the back of a chain, there are even more bonus points. There is only one Gold Mini Mario per level, and are only found in certain levels. In an earlier version of the game, they appeared on every level, in the top screen in screenshots.
Mario and Donkey Kong: Minis on the Move
A Gold Mini Mario also appears in Mario and Donkey Kong: Minis on the Move. It can be seen in the Toy Collection and is unlocked by collecting all 230 stars in the game. While the other toys had remixes of the main theme, this toy has a remix of the Super Star theme.
Mario vs. Donkey Kong: Tipping Stars
Gold Mini Marios reappear in Mario vs. Donkey Kong: Tipping Stars in levels B-23 and especially in B-24 from the Bonus 3 set. They can also be bought from the Workshop Store for 5,000 stars, then used by the player in the level editor. They act just like the other Minis, patrolling an area back and forth and interacting with the environment.