Captain Koopa Troopa Trial (Gold)
From the Super Mario Wiki
Captain Koopa Troopa Trial (Gold) is the secret bonus level of Gwarhar Lagoon in the Minion Quest: The Search for Bowser mode in Mario & Luigi: Superstar Saga + Bowser's Minions. In order to obtain this level, the player has to use certain amiibo to unlock it.
This is the sixth of seven bonus levels that involves a captain battling enemies by themselves. Captain Koopa Troopa (Gold) is the selected captain to enter this level.
The level has only one battle, with there only being a single Elite Troopea. During the battle, the Elite Troopea will initiate a Pass the Bob-omb event a few times, making the level a bit more challenging.