A/N: Written for the Sailor Moon Flash Bingo on the Sailor Moon Fanfiction Challenges forum (link in profile), #169 – Mistress 9.
Not sure where it says Pharaoh 90 is one of Chaos' many reincarnations, but it's on the wikia page, and this is what sprung up from that little morsel of information.
Chips of Reincarnation
Chaos had reincarnated herself into many forms. Pharaoh 90 was one of those who'd grown from the flakes of skin and hair that had escaped destruction and became an independent entity.
Yet he had the same goal as Chaos, deep down: annihilation. He fought the Senshi of light in the same way as well: stealing their purity, their hearts, their souls. But he was weak; Chaos was so strong only Cosmos could fight head to head with her, but destruction alone had defeated Pharaoh 90.
Sailor Saturn: the Guardian Senshi of Destruction. Though she hadn't destroyed Pharaoh 90 as per her name. She was weak as well. Not like Cosmos, just as Pharaoh 90 was not like Chaos.
Once, there was only Chaos and Cosmos. That was before endless cycles of reincarnation had filled the universe with lesser beings.