Army Dillo is first seen in Jungle Japes where he is guarding the first key. Army Dillo attempts to take out Donkey Kong but fails. During sometime afterward, Army Dillo is given a second chance and fights his old enemy Donkey Kong at Crystal Caves. However, Army Dillo is once again defeated.
During the Jungle Japes battle, Army Dillo mainly attacks by hurling fireballs at Donkey Kong. He will then roll up into his shell and attempt to run over Donkey Kong. By the time of Crystal Caves, Army Dillo has been upgraded and possess a new attack which involves him flying up and sending a large shockwave at Donkey Kong.
For both battles, the key to winning is to keep moving. When Army Dillo starts hurling fireballs, Donkey Kong should run around in a zig-zag from to avoid them without taking damage. When Army Dillo starts laughing, Donkey Kong must grab a TNT Barrel and hurl it at the monster. Donkey Kong must do this three times in total to win.
- Army Dillo is the only boss in Donkey Kong 64 to be fought by the same kong twice.
- Army Dillo is also one of two bosses that is fought twice in the game. The other being Dogadon.
- The name Army Dillo is a pun on the animal, armadillo. The "Army" part of his name comes from his various of weapons that could be used for war.