The overall crew strength seems to be rather weak, despite having five bounties, two Devil Fruit users, and each commanding several crews of pirates (which is a large group altogether, similar to the Krieg Pirates). Three of the captains, Boo Jack, Skunk One, and Pin Joker were quickly defeated. Honey Queen, despite holding a Logia-class Devil Fruit, was easily captured. The overall leader, Bear King, was the only one who put up a longer fight, but was regardless defeated.
The King Cannon (キング砲,Kingu Hō?) is the ultimate weapon of the Trump Siblings. They had forced the scientists of Clockwork Island to build the weapon in order for Bear King to become the Pirate King. The weapon was ultimately destroyed when Luffy threw one of the bullets back and caused the glass ground below the cannon to shatter, with both the Cannon and Bear King falling off and exploding.
The King Cannon is a four-wheeled tank with a giant cannon barrel that resembles a screw mounted on it, decoratively designed with the four card suits (spade, heart, club and diamond). On the left side of the tank is a meter gauge that shows how much charge is achieved before the cannon can be fired, and the back is a feed ramp for the giant bullet-shaped cannonballs with drill-design. The cannon can fire these bullets with drilling force, which is strong enough to cause intense impact to create shock waves that can spread throughout a portion of the ocean.
The siblings ruled over Clockwork Island for years in their headquarters, the Trump Castle, and forcing the scientists to build the King Cannon, a cannon that can fire devastating drilling cannon bullets. They planned to use the King Cannon to make their leader into the Pirate King, but met opposition from the Straw Hat Pirates alongside with Borodo and Akisu. Eventually, the entire Trump Siblings were defeated by the Straw Hat Pirates.