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.
After the sudden return of Princess Bubblegum's Uncle Gumbald, he immanently plans to destroy his niece, having her subjected to his Dum Dum Juice, as she did to him 800 year prior. Gumbald went on to form a Candy city-state known as Gumbaldia. Gumbald built an army of Cake Soldiers, who he presumably created. Concerned and angry on the matter Princess Bubblegum saw war as the only answer, despite Finn's protest.
The war was set to begin and was given the title the Gum War. The Candy Kingdom army consisted of Banana Guards and the Gumball Guardians. The army introduced new type of Banana Guard, Banana Guard 500s. These guards had large, round heads, grey visors with a radar attached, and a jetpack. They carry a pink gun and are planned to be used in the Gum War. In addition as group of Princess Bubblegum's friends and allies were set to fight in the war as soldiers including as Finn, Jake, Marceline, Colonel Candy Corn, Lumpy Space Princess, Flame Princess, Cinnamon Bun, Lady Rainicorn, Lemongrab, Duke of Nuts, Huntress Wizard and Slime Princess. However Finn convinced PB and Gumbald to make amends and the war was unfought, though the army and allies did fight in the battle against GOLB who suddenly arrived only moments after the war was called off.