Gold Mario

Gold Mario and Silver Luigi are forms debuting in New Super Mario Bros. 2, acquired by grabbing a Gold Flower. In this form, Mario can shoot big Gold Fireballs and Luigi can shoot big silver fireballs, defeating any enemy or breaking any block that is within a certain distance or any that they touch, turning them into coins. In addition, the shockwave will also empty out several non-brick blocks/brick blocks that are secretly containers.

In this form, the character becomes a glowing statue made of gold. In Luigi's case, he becomes a glowing statue made of silver. In both cases, the form resembles Mario's metal form since gold and silver are a type of metal. If Mario/Luigi reaches the Flagpole in this form, he receives a coin bonus. The higher the pole is grabbed, the more coins he will receive. Gold Mario/Silver Luigi reverts into Fire Mario/Luigi upon clearing a stage, making it impossible to keep this power-up between levels. Gold Mario is able to defeat almost every enemy in the game, including Boos, Thwomps, and even Spiked Balls (though not giant ones), rivaling the power of Hammer Mario. He can also defeat bosses, but they take more than one hit to be defeated (with the exception of Bowser). The power-up, however, has no effect against the Boohemoth.

Gold Mario makes a return in Mario Golf: World Tour, but this time as a DLC character, where he is unlocked by purchasing all three course packs, either through the Season Pass, which unlocks him immediately, or by buying them all separately, in which case he is unlocked after the last one has been bought. Here, he seems to replace Metal Mario and Shadow Mario as the second Mario.

Trivia

 * In the first Animal Crossing game, there are two furniture items based off of Mario and Luigi, the Mario Statue and the Luigi Statue. The Mario Statue is actually golden, and the Luigi Statue is silver.
 * The model for the gold/silver fireballs always spins clockwise, even when thrown to the left.
 * If the player performs the infinite 1-Up trick using a shell and a set of blocks in a stair formation as Gold Mario/Silver Luigi, the shell will explode into a shower of confetti after the 24th hit, accruing 1050 coins total from the coin multiplier.
 * Gold Mario's artwork in Mario Golf: World Tour is identical to Metal Mario's artwork from Mario Kart 7. The only differences are that he's leaning on a golf club rather than a stack of tires, and his eyes aren't blanked out. Also, when he gets a good shot in Mario Golf: World Tour, he talks like regular Mario instead of a warbled voice like Metal Mario and Shadow Mario.