Anyway, In Ultimecia's age, they made a machine that could let you control someone in the past, much like Ellone's special ability, and Ultimecia was using that maching to control Edea, right? Why, if Ultimecia was really Rinoa, would she have those lizards attack her?

Don't tell me "memory loss," because even those with amnesia remember what they look like, and Rinoa, at that time, was at the age were your body doesn't make too many dramatical changes until you get old and wrinkly. I still think Ultimecia is just some random sorceress who went crazy, or possibly Matron (that was her name, right? Edea's real name).
http://www.script-tease.net/kristian/

PS: Edea was her real name, not MAtron, which is just a "nickname" like "mummy".
Also, Edea cannot be Ultimecia because at the end of the game Edea is not a sorceress, while Ultimecia is.