Look, I don't know much about Chibi Chibi, but here's what I DO know...
Chibi-Chibi first appears in Sailor Moon Stars. She falls from the sky, much like Rini did in Sailor Moon R, with an umbrella in her hand. No one knows who she is or where she came from. She is 3 to 4 years old, and she often says the words, "chibi chibi, chibi chibi...". Rumor has it that Chibi Chibi is Sailor Moon's future self as Sailor Cosmos.(WHICH SHE IS)
A.K.A. Chibi-Chibi Moon (or Mini-Mini Moon),
Birthday: June 30
Hobby: Bugging the Starlights
Favorite food: doughnuts/cake
Strong point: Getting people to like her