Mega Sledge Bro
From the Super Mario Wiki
Mega Sledge Bros are giant Sledge Bros that made their debut in Mario Party 10, where a single Mega Sledge Bro appears as a boss. Its minigame, Mega Sledge Bro's Card Chaos, involves cards and Bullet Bills. The players must remember the number of Bullet Bills on the cards, because the Sledge Bro hides them after a moment. After that, the players have to choose a card to launch a bullet on the Sledge Bro. The number of bullets is from one to three. Some cards can have hammers on them. The Sledge Bro will throw an hammer on the player who choose one of these cards.
Mega Sledge Bros make a minor appearance in Super Mario Maker and Super Mario Maker for Nintendo 3DS when placing a Super Mushroom on the Sledge Bro. It will grow bigger than a usual Sledge Bro, but will then sneeze the Super Mushroom out, shrinking it back to normal.