This article is from the 2006 series of SMBZ and is no longer canon.
The Smithy Gang is an evil organization composed of the mechanical monstrosities created by the villain Smithy. The primary goal of the Smithy Gang was world domination, which it came close to doing during the events of Super Mario RPG: Legend of the Seven Stars. Additionally, Smithy wanted to fill the world with weapons and destroy the power of wishes by shattering the Star Road. Their main base of operations was Smithy's Factory, which existed in a dimension beyond Mushroom World. Their secondary base was Bowser's Keep, which the fiend Exor occupied during the beginning of their invasion. The sword creature acted as a gateway between the two worlds, allowing Smithy's forces to overrun Mario's world in Super Mario RPG: The Legend of the Seven Stars.
It was assumed they would appear in Super Mario Bros. Z, as Axem Rangers X appeared and had told that Smithy was alive. Also, Alvin-Earthworm said there would be a second season and also said it would have Smithy, together with the Axem Rangers who apparently would again appear with a new member: Axem Ranger Blue, as the antagonists. Alvin said the Smithy Gang and some of its members would make an appearance.