Time of Awakening

The Time of Awakening (目覚めの時, Mezame no Toki) is an event that appears in the Super Smash Bros.' Sonic series created by Yuji Naka. It is a major global phenomenon that occurs naturally on the planet every few millions of years where the planet is broken apart by Dark Gaia following the beast's return to full maturity in an attempt to destroy the world. Following this cataclysmic break-up, the world is put back together by Light Gaia, who awakens at the same time and returns Dark Gaia to dormancy before going back to sleep as well.

"Dark Gaia grows over millions of years, then rises to destroy the world. And yet I stop him, and put it all back together again. We've been doing this over and over, again and again... since the very beginning of time."
 * —Chip.

Origin
It has been speculated by Prof. Pickle that the time of awakening was instigated by the planet itself to have a balance between light and darkness. The genesis for the event took place in the beginning of time with the birth of Dark Gaia and Light Gaia following the planet's creation. Following their purposes, Dark Gaia sought the planet's destruction while Light Gaia sought to protect it from his dark counterpart. In the end, Dark and Light Gaia began an endless cycle of destruction and rebirth of the planet. In this cycle, Dark Gaia would sleep in the earth's core for millions of years to gather negative energy and then emerge from the core as Perfect Dark Gaia, splitting the world apart. Light Gaia would then awaken, return Dark Gaia to sleep, and restore the earth before going back to sleep as well. If Dark Gaia should succeed its mission, all life on the planet would perish, and the death planet would enter a deep slumber until Light Gaia's arrival. The time where these two deities would awaken, rising up to their full potential, became known as the time of awakening.

Occurrences over the ages
Over the eons, the time of awakening would continuously repeat itself. The second-to-latest time of awakening is said to have occurred some tens of thousands of years ago. This event became a legendary disaster that threatened the existence of the world, and the knowledge gained from it was recorded in the Gaia Manuscripts.

Premature Time of Awakening
In Sonic Unleashed, Dr. Eggman initiated the time of awakening himself with his Chaos Energy Cannon which forced Dark Gaia to awaken so he could harness the beast's energies to build Eggmanland. However, this was not a proper time of awakening as it happened too early. As a result, Dark Gaia dispersed around the globe due to immaturity, and Light Gaia lost his memories.

When Sonic the Hedgehog and Light Gaia confronted the fully reassembled Dark Gaia in the planet's core, Light Gaia called the Gaia Temples to form the Gaia Colossus, pronounced that the time of awakening had now truly arrived. With the help of Super Sonic, Light Gaia defeated Dark Gaia, bringing the time of awakening to an end once more and restoring the two deities' cycle.