Many Dragon Ball fans would agree that the Super Saiyan 4 form seems like a more accurate representation of a Super Saiyan God than what was shown in Super given its ape-like aesthetic, it’s link to Oozaru (which is oftentimes described as a god), and the fact that the transformation alone is more powerful than the magic of the Dragon Balls (which were created by the God of Earth, Kami). Well, in one episode of GT, those fans nearly got their wish as Super Saiyan 4 almost became the base form of Super Saiyan God (theoretically).
The idea of Super Saiyan God as fans know it today was introduced in the Dragon Ball Z sequel series, Dragon Ball Super. While no Saiyans had unlocked a form called Super Saiyan God upon the launch of this series, they quickly learned how to reach that level through an ancient Saiyan ritual. The ritual dictates that five Saiyans must offer their ki to a sixth, and that sixth Saiyan will then become a Super Saiyan God. Goku is the recipient of this power, making him the first Saiyan in known history to become a Super Saiyan God–though GT confirms he could have unlocked it a lot sooner (in terms of real-world release dates, of course).
SSJ4 Goku was One Saiyan Away from Completing the Super Saiyan God Ritual in GT
In Dragon Ball GT episode 38 (written by Toshinobu Ooi, directed by Osamu Kasai, produced by Toei Animation), Goku is facing off against the villainous Baby following Baby’s fusion with a reluctant Vegeta–marking the birth of the ultra-powerful Baby-Vegeta. In this episode, Goku is a Super Saiyan 4 while Baby-Vegeta is a sentient Golden Great Ape, meaning these two power-houses are throwing enough energy blasts at each other to level planets–which also means they’re depleting themselves of energy fast. After Baby-Vegeta is rejuvenated thanks to a machine invented by a brainwashed Bulma, he is as good as new while Goku is in a much more weakened state. So, Goku needed the assistance of his fellow Saiyans who freely offered their ki to get Goku back up to full strength, and those Saiyans were Trunks, Gohan, Goten, and Pan.
When the four Saiyans gave their energy to Goku in this episode, all of them joined hands and focused their ki towards their champion in a manner that was essentially identical to the Super Saiyan God ritual. In fact, if Goku had just one more Saiyan giving him their energy, he would have become a Super Saiyan God whether he meant to or not, and he would have been granted this power while still in the form of Super Saiyan 4. Unlike other Super Saiyan transformations that just change the hair color/style of a Saiyan and nothing else (aside from a massive power-up, of course), Super Saiyan 4 alters a Saiyan’s entire body (clothes and all). Saiyans don’t just channel the power of Super Saiyan 4 like they do with other Super Saiyan power-ups, they literally become a Super Saiyan 4 the same way they become a Super Saiyan God.
So, what would happen if a Super Saiyan 4 participated in a Super Saiyan God ritual? Presumably, it would mean that the Super Saiyan 4 Saiyan would unlock god ki while in their SSJ4 form, allowing them to elevate that transformation even further and become the literal pinnacle of Saiyan evolution. Or, the Saiyan would simply revert to normal and get red hair along with their god ki, with no integration of their Super Saiyan 4 transformation. Until SSJ4 makes its inevitable appearance in the current Dragon Ball continuity, there will be no way of knowing what this mixture would produce. One thing fans know for sure, though, is that Super Saiyan 4 was potentially almost Dragon Ball’s first Super Saiyan God–if only one more Saiyan was around to offer Goku their ki.