Getter Robo/WMG

Flubber is a manifestation of Getter Rays

It's green, sentient, physics-defying, has the ability to split and recombine itself, shows an interest in mimicing humanity, and is used as a source of power for vehicles. Not to mention it was let into the world by a Mad Scientist.

The Getter is responsible for the creation of Sparks

It spreads to new realities by influencing their inhabitants until one of them succeeds in creating a Getter Robo. Its pilots may also be Sparks, given that the few who can bring out the full power of a Getter tend to be mentally unhinged.

All versions of Getter Robo exist as Alternate Universe versions of each other

Based on the endings of New and Armageddon

Alternatively, what we seen at the end of Armageddon were:

Previous incarnations of Getter Robo, including some we had never seen. Some bits of dialogue seems to support that.

• • This leads to theory that Getter Robo Universe is reseting itself.

Getter Robo Universe/Multiverse is connected with Warhammer 40,000.

And dimension at the end of Armageddon is Warp - red/purple background and monsters with human features on hon-human bodies that wouldn't stand out in Warhammer 40.000 sorta leave that impression.