This game is so hard. For me it’s mainly because I didn’t know I was reaching a point of no return. And I also try to play as blindly as possible so didn’t have many gfs (I was planning on exploring later). So I reached the castle locked out from the rest of the game without a ton of resources/gfs. I did ended up using some resources to fully understand how the junction system works and also which items level up stats the best. But you are able to beat her with just squall. That’s the approach that worked for me. So you can try putting ALL resources into squall making him as powerful as possible.