Well, I dont know what is exactly the meaning "The Strongest GF in Squall's mind" , does it mean "Squall thinks Griever is the most powerful" or "Griever just Squall's imagination"???
I heard there were two popular theories....
1. Rinoa is Ultimecia in the future. As time goes by, Squall Cs are all dead, leaving her all alone, Sorceress with no knights will turn evil just like Edea said. And Rinoa owns Squall necklace or ring? whichever with Griever engraved on it in the Disc 2 I think..... perhaps Griever does exist and Ultimecia summons it then says what Squall said to her "The Most Powerful GF".
2. Ultimecia picture out Griever from Squall's mind then summons it into reality and figure out that Shockwave Pulsar is the most powerful enemy skill + all-enemies attack from Quistis's mind then transcend that ability unto Griever. She could say Griever is the most powerful just because she created it from other's thoughts of what was actually "the strongest/hardest to be defeated" for them. So basically, the characters fight their strongest imaginary creature or sumthin like tat. Ultimecia took benefit from it but totally fail, perhaps she didn't that genious in magical skills to create something real from imagination directly.... or perhaps Squall Cs. imagination didn't that great if applied in reality. :rolleyes2 :eek: :D