- Confirmed by the plot of Devolution, where a fragment from the Getter Emperor falls between universes to end up in the Devolution world and ignite the plot.
- This leads to theory that Getter Robo Universe is resetting itself.
- Confirmed, sort of, in Alpha 3. They, along with Beamler, Psychic Power, STMC, Anima Spiritia and Ide are aspect of Akashic records (fate).
G-stones? G-stones are what happens when you take such a being (or a fraction of it, at least) and punch it in the face until it respects you. You teach it emotion, and when it understands your drive, it allows itself to evolve beyond the end of evolution.
Jossed. Ultimately it didn't go in full detail any further than the manga, ending on a cliffhanger as Saint Dragon appears from the depths of the Saotome Laboratory during the fight between Takuma aboard Getter Arc versus Kamui in Bug. Based on what we are shown happens after the very sudden timeskip, it can be surmised that :
- Bug clashing against Saint Dragon caused either the outright destruction of the Earth, or made it impossible to sustain human or saurian life, thus starting the journey of humanity through the stars. Just as Getter Emperor had planned.
- Kamui ultimately got defeated and was made responsible for the whole debacle, leading to him being jailed on Mars where the survivors of humankind and saurians emigrated.
- Baku was shown to have premonitions of the future, and it could be explained by Getter Emperor being a singularity spanning multiple universes and the timeline where it exists/will be born. Therefore, his premonitions could be seen as a byproduct of the Getter Rays nudging him in the right direction to be born and ensure the singularity is formed, since Getter Emperor remembers events.
- However, as stated, it doesn't remember the events after Shin Getter Robo got sent to Mars, meaning the gap in the memories might be a chance to avert the Bad Future. This has to be where Arc comes into play as trying to fight the nascent Getter Emperor (confirmed to be so, since it evolved on Mars and speaks in Ryoma's voice).
- Therefore, one can surmise Baku tried to understand better Emperor to understand how to influence it since it's neither good nor evil.
It would have been nice to have the full story spelled out, but we can piece the above together based on what elements we have been given.