Gold Mario

Gold Mario/Silver Luigi is a form debuting in New Super Mario Bros. 2, acquired by grabbing a Gold Flower. In this form, Mario can shoot big golden fireballs and Luigi can shoot big silver fireballs, defeating any enemy or breaking any block they touch, turning them into coins. In this form, the character becomes a glowing statue made of pure gold. In Luigi's case, he becomes a glowing statue made of pure silver. In both cases, the form resembles Mario's metal form as well as the brothers' ice form from Super Mario Galaxy.

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. Interestingly, the Mario Statue is golden, and the Luigi Statue is silver.
 * In Mario Golf, one of Metal Mario's palette swaps resembles Gold Mario.