The Candy Kingdom's army is primarily composed of the Banana Guards. The guards are usually armed with spears. In the episode "Susan Strong," it is shown that the Candy Castle has an armory full of a variety of candy weapons. In addition, the Candy Kingdom is shown to have a sizable cavalry force in "Reign of Gunters." Although the Banana Guard army primarily operates within the walls of the Candy Kingdom, they are sometimes sent out by Princess Bubblegum to deal with major threats such as Gunter or Rattleballs.
The Gumball Guardians also act as a main line of defense within the Candy Kingdom and are stationed on the kingdom's walls. They are programmed to protect the Candy People from any form of danger and to enforce the Royal Promise. They are able to detect and intercept any evil force that approach the Candy Kingdom. They are shown doing this in the episodes "Slumber Party Panic," "Mortal Recoil," "Reign of Gunters," and "The Lich."
Although melee-based weaponry is most prevalent in the Candy Kingdom, their military is shown to have access to superior technology when compared to most other kingdoms. Along with the access to advanced robotics, the kingdom is equipped with candy cane rifles and candy helicopters, as shown in "Hug Wolf" and "Princess Cookie" respectively. This, along with a large number of Banana Guards, makes the Candy Kingdom's military a formidable force in the Land of Ooo. Princess Bubblegum was confident enough that in "Bad Timing," she immediately threatens Lumpy Space Princess with a declaration of war on Lumpy Space after getting assaulted by her.