About the Elder Gods
The Elder Gods are the supreme deities of the universe. Where as other human Gods (Bill Gates, Montana, me, Travonni, Maxwell, etc.) only have jurisdiction over a single country or planet and typically represent an thing, the Elder Gods are more ethereal and have power in all planets. The blue faces of the Elder Gods are seen in Mortal Kombat 4, and the appearance of Shinnok in the same game, suggest that natural born Elder Gods have blue-gray skin and a humanoid appearance. Another different source of their form is found in Return of The Dragon King's Konquest Mode where an inverted dialogue states that, in their purest form, the Elder Gods resembles the Mortal Kombat Dragon logo. Beings with this form can be seen in Onaga's unused ending picture found on Deception's Krypt, in Armageddon's Konquest, where Steven finds an inscription of his father talking to dragon-shaped figures, that he states to be the Elder Gods, and Captain Marvel's ending in Mortal Kombat vs DC Universe. Their true nature and extent of their powers remain a mystery but is believed to be Omnipotent having existed long before the Mortal Kombat tournament and can foresee events.
Before the planets of Universe came into existence, there was the One Being, which comprised all of known reality. The Elder Gods waged war and created the Kamidogu, powerful weapons used to shatter the One Being. The Elder Gods then created the planets from its body, with Earth as the center of power.
Even though the One Being was shattered, its divided mind plotted through exceptionally powerful individuals. It acted through Onaga at first, and would later through Shao Kahn, both unaware of its manipulations. It also commands Onaga during Mortal Kombat: Return of The Dragon King to fuse the Kamidogus into one, and apparently only Ermac is able to notice its vague presence.
The Elder Gods' rule of non-interference in mortal affairs that do not threaten their own existence was evident when Shao Kahn, Emperor of Outworld, merged Earth with Outworld to reclaim his wife Queen Sindel, in direct violation of the secret rules of Mortal Kombat. Raiden begged the Elder Gods to stop Shao, who was required by those rules to win ten consecutive Mortal Kombat tournaments before he could take Earth, but the Elder Gods did nothing. Thus, the Elder Gods show no signs of being truly benevolent or malevolent towards the various threats posed to Earth. They usually only intervene if the villain of the world poses a potential threat to them or defy their will.
Their non-intervention nearly caught them unaware when Shinnok escaped from the Never Never Land and attacked them directly but due to their status and Raiden's forces defeating Shinnok, this was prevented. Tousand years earlier, rumors had it that they had cursed Shang Tsung to consume the souls of other mortals to maintain his existence, either not knowing or not caring that his need to devour mortal souls would lead to him learning the location of Shinnok's Secret Amulet. Eventually that knowledge would reach Quan Chi, who used it to free Shinnok and take the amulet for himself. Shang Tsung's abilities however were taught to him from Shao Kahn centuries ago. Thanks to the intervention of Raiden, Fujin, and the champions of Earth, Shinnok was stopped. For this, Raiden was rewarded by being made an Elder God himself and as a result promoted Fujin as the new Protector of Earth to take his place.
However, Raiden soon shed himself of this status when the Deadly Alliance arose as a threat to Earth. Divesting himself of Elder Godhood to lead his mortal pals into direct combat, this time Raiden's efforts were thwarted, with all of his allies either being killed or disabled. The threat posed by the Deadly Alliance was rendered moot, however, when The Dragon King appeared at the scene where Raiden had just been defeated by the two sorcerers. For centuries Onaga had lain in wait from beyond death to be resurrected and complete his conquest of the planets. Raiden, Shang Tsung, and Quan Chi were unable to stop him. As a last effort, Raiden released his godly ball, causing a massive explosion, yet Onaga was alive. Soon, all of Raiden's energies reformed in Outworld, and were evil. This drove Raiden to believe that he could neither trust the Elder Gods nor his mortal comrades. Most of all, Raiden was furious with the mortal Shujinko for being duped into aiding the Dragon King's return.
Ironically, this time the Elder Gods did interfere. Now aware of a possible threat to them and the planets, because Onaga had acquired all the Kamidogu and the Amulet, the Elder Gods summoned Scorpion to act as their champion and destroy Onaga. In exchange for his services, they agreed to resurrect his clan. However, after Onaga's defeat, the Elder Gods, for an unknown reasons - resurrected Scorpion's clan as zombies, rather than as fully restored humans. Scorpion perceived this as an act of betrayal on the Elder God's part and turned against them.
In Mortal Kombat: Armageddon, it is revealed that the Elder Gods foresaw that one day the Mortal Kombat tournament would be corrupted, and that the participating warriors would become too powerful and too numerous, jeopardizing the safety and existence of the planets. They demanded a safeguard be put in place to prevent Armageddon. Argus, the protector God of Edenia, and his wife Delia, helped constructed a hidden pyramid and created an elemental warrior known as Blaze to watch over the planets and judge when its participants became too dangerous. When the time came, Blaze would call out, awakening Argus' two sons, Steven and Daegon, who would challenge Blaze on top of the pyramid. Whichever son won the battle would become the new god of Edenia, and be given the power to decide the fate of every other warrior. Should one brother be victorious, the kombatants would be stripped of their power. Should the other be the victor against Blaze, the kombatants would be stripped of their lives. Elder God characters can be created or promoted from a prior status, but the necessary parts must be unlocked in Konquest mode. If all the necessary parts are collected, then your character's appearance would resemble a man or woman in golden armor. Called "The Elder God".
The Elder Gods also appeared in both Raiden's vignette and the Story Mode of Mortal Kombat 9. In the last chapter Raiden was about to face the same fate as his future self, but the Elder Gods (as dragons) descended and healed him. Shao Kahn tried to merge the planets without the necessary tournament wins so the Elder Gods helped Raiden defeat Shao Khan and imprisoned the emperor.
The Elder Gods imprison their evil "brother" Shinnok with their powers and returned the planets back to their natural state. In Mortal Kombat: Annihilation, they are represented by ethereal beings of fire (possibly Blaze), air, water, and weather and they live in an ancient arena-like catacomb called the Eternal Palace, which is their place of worship, called the Temple of the Gods. Their brother, Shinnok, who is the Elder God of Darkness, is arch-enemy of Raiden and like a father to Shao Kahn, according to MK. And he wishes nothing less for power not only over all planets, but over the other Gods as well.
He favours Shao Kahn, considering too be powerful and caring to be his son. Shinnok orders Shao Kahn to kill Raven, while guiding him in his path to merging the parallel universes of Earth and Outworld.
Shinnok is later stopped by two of his fellow Gods who appeared in their human forms, while still possessing and representing the elemental powers of fire and water, since they finally learned of Shinnok's plot to rule the universe. After Liu Kang and his buddies won the fight against Shao Kahn and his warriors, the Elder Gods later imprisoned Shinnok for a month and restored all the planets back to their natural form. They later resurrected Raiden and offered him Shinnok's position in their ranks.