The Rebel Army required an affordable tank that had a good range of mission profile, with balance between firepower, mobility and survivability. They already knew that what's left of the Regular Army was producing and amassing a fleet of their own SV-001s , and Girida-O was meant to be its direct opposition. Even though classified as an MBT, Girida-O fills the role of a medium tank, complementing heavier tanks still in service such as Di-Cokka or Iron Iso. Girida-O sacrifices protection in favour of a smaller frame and faster speed. . Due to design flaws tank operators often ran over their own infantry support. In the course of Modern Wars the tank has seen a number of upgrades.
Girida-O's chassis is utilised by the Rebel Army for other purposes, such as material transportation and bulldozing. A utility variant with the turret removed and equipped with a front bulldozer blade and a hydraulic dumper bed has been nicknamed "Dararin Dara Dara".
Other factions later involved in Girida-O's production are Amadeus Syndicate and the Ptolemaic Army. The latter faction based on data stolen from the Rebel Army has developed its own variant (Ver. P.M.)  with improvements over the original, such as better armour protection without sacrificing mobility, as well as a superior cannon with an improved loading mechanism and higher stopping power . Additionally, the problem of situational awareness of the crew (that had plagued the original model) has been fixed, reducing infantry accidents to a minimum. The resulting AFV is also more expensive to manufacture.
A very tricky tank to defeat, as its shots fly in an arc. One of the few ways to fight it is to go very close to it and crouch continuously shooting it, however there is a risk of being ran over by the tank. Another way is to stay out of its line of sight and shoot it from afar. Using grenades is recommended.
|Girida-O: the original, most common variant.|
|Girida-O (Universal Metal Slug)|
|Girida-O "Dararin Dara Dara": a utility variant that can dump I-beams onto players.|
|Girida-O (Metal Slug 3)|
|Girida-O: an improved variant that fires more shots.|
|Girida-O Ver. P.M.: a Ptolemaic variant that is faster and better armored.|
|Future Girida-O: an improved variant that is faster and better armored. It fires magnetic shots that can pierce through weak rocks and can make the latter crush the player near them.|
- Girida-O's design is largely influenced by American tanks of the World War II.
- (Found in Metal Slug 6 standalone, not in anthology) An early concept image depicts Girida-O with a mine plough and a machine gun on top of the turret. Its treads are similar to the Di-Cokka's.
- The early concept depicted at the right resembles a M4A3 Sherman Jumbo with frontal track skirts, though it looks plump.
- Single-shot grenade launchers  are mounted on Girida-O's turret, however those are never used on-screen.
- This tank is currently the only one whose chassis had been re-purposed for utility.
- Its treads in the game are similar to the SV-001 (Metal Slug).
- The original Girida-O's cannon goes back from recoil when it fires. However, the Ptolemaic variant's cannon goes forward instead when it fires, giving it a little more range.
|Combat||Di-Cokka | Bull Chan | Girida-O | Iron Iso | Melty Honey | MV-280B | Mini-Bata | M-15A Bradley | LV Armor | MV-280C|
|Support||MV-280A | Dararin Dara Dara | 3-ton Utility Truck | Landseek | Nop-03 Sarubia | M-3 Rocket Launch Support Van | Double-Decker Bus | MG-36 | Ferry Boat | Subway | Turrets | Morden Saucer | Walking Locomotive | Garbage Fortress | Mine Carts|
|Aerial||R-Shobu | MH-6J Masknell | Flying Tara | Eaca-B|
|Marine||Hammer-Yang | Jet Hammer-Yang | U25U | Mini-Sub 88|
|Vigilance||Mosque Artillery | Patrol Robot | Supervisory Camera | Sensor Mine | Morden Robot | Metal Mole | Laser Drone | Pods | Robot Walker | Balor|
|Ptolemaic||Black Hound | Hover Vehicle | Hover Unit | A.P.C. | Ptolemaic Slug | Wall Drone | Units | Ptolemaic Saucer | Mammoth Tower|