This ultra-heavy mobile fighter serves as the commander of the Death Army's ground forces. The monstrous Grand Gundam was far larger than most Mobile Fighters, barely resembling a humanoid form due to its disproportionately large limbs compared to its torso and head (which were about the size of a normal Gundam's head and torso). Its armor could withstand unbelievable amounts of damage, including impact with a rock about as large as itself. It normally moved in a quadrupedal stance, but could stand on two legs if the situation warranted it.
In addition to using its sheer bulk to crush enemies, the Grand Gundam came with several armaments. The "Grand Horns" flanking its head were enormous tusk-like spears which could extend and charge themselves with energy. Its main weapons were the four "Grand Bomber" cannons on its shoulders, which could fire near-unlimited amounts of destructive charges. Each cannon was also equipped with a hand that could be fired on a durable cable. These hands could be used for precision attacks, to cut off enemy movement, or to help the Grand Gundam move more efficiently.
As the 13th Gundam Fight continued, the Devil Gundam created Four Heavenly Kings for its protection: Master Gundam, Grand Gundam, Gundam Heaven's Sword and Walter Gundam. The Grand Gundam first appeared when three of the Heavenly Kings attempted to stop Domon Kasshu from reaching the Gundam Fight Finals on time.
When this failed, the Grand Gundam returned again during the Finals. While George de Sand fought Gentle Chapman's John Bull Gundam, the Grand Gundam appeared out of a cloud of black mist after the latter was badly damaged. George barely managed to repel the Grand Gundam by shooting it in the eye with his Rose Bits, forcing it to revert to the John Bull Gundam.