Perhaps you can help by uploading a picture of KH Final Mix render.
After sealing the Keyhole in Deep Jungle, Sora returns to Traverse Town and tests the legend about the Second District bell by ringing it three times, revealing the world's Keyhole within the district's fountain. However, as the group goes to seal it they are attacked by a Guard Armor, and though they defeat it, it transforms itself into the stronger Opposite Armor and attacks again. After it is destroyed, they are able to seal Traverse Town's Keyhole.
A second Opposite Armor appears in the Hades Cup.
The Opposite Armor's body is made of identical components to the Guard Armor, the key difference between the two being that the Opposite Armor's components are inverted. Thus, its torso is upside down, with the collar-like additive now being on its underside. The Heartless emblem is emblazoned on the center of the armor. Its head is the only part of its body that is not actually inverted, but instead its faceplate drops down. This exposes that the Heartless does in fact share the pitch-black face and glowing yellow eyes of other Heartless. Both of the Gauntlets now act as the Opposite Armor’s legs, and it walks on its hands.
The Hammerlegs take the places of its arms, and its feet replace its armored hands. Curiously, the Opposite Armor's Heartless emblem is right side-up, despite the Guard Armor's torso being flipped upside-down. However, viewing it's model in Jiminy's Journal reveals it to have two heartless emblems, one on the front, and an up-side-down one on it's back.
In Kingdom Hearts Final Mix, the violet sections of the Opposite Armor are silver, its torso gains red, yellow, and blue stripes on its upper half, its head becomes red with yellow spikes, and the additives on its top and upper rims become blue and yellow, respectively. Its fingers become grey, while its feet become red.
The Opposite Armor's name references its armored body, as well as the fact that its body parts are the inverted pieces of the Guard Armor's body.