Gold Koopa

New Super Mario Bros. 2
A Gold Koopa is a Koopa Troopa under the effects of a Gold Ring in New Super Mario Bros. 2. When a Gold Shell is thrown, a path of coins will follow it. Whenever a Gold Shell is thrown at an enemy, an increasing number of coins will be earned for each enemy defeated.

Mario & Luigi: Superstar Saga + Bowser's Minions
In Mario & Luigi: Superstar Saga + Bowser's Minions, a gold variant of Captain Koopa Troopa is unlocked whenever the Koopa Troopa amiibo is scanned in the Minion Quest: The Search for Bowser mode.