From the Super Mario Wiki
Captain Goomba is an oversized Goomba in Mario Party 8. He appears at the end of Goomba's Booty Boardwalk and gives characters free Stars if they reach him. As his name implies, he is a captain of a ship and has a few Pirate Goombas serving under him.
This is a little bit different in Star Battle Arena. In this mode, he still gives characters a star, though it costs 50 coins. Whoever gets the star from him first before their opponent does wins. However, if characters arrive with less than 50 coins, Captain Goomba will let them hit a Coin Block in a Coin Block Area for a chance of winning 1, 5, or 10 coins. After that he will tell his crew of Pirate Goombas to take them back to the start using a cannon.
Captain Goomba is the leader of a crew of Pirate Goombas, which are Goombas with green pirate bandannas. They appear on a Green Space. If a player lands on their Green space, the three Goombas will exclaim that "landlubbers" are not allowed to meet their captain and are only worthy to be cannon fodder. Upon saying this, the Pirate Goombas immediately surround the character, load them into the cannon, and blast the player back to start.
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