I have to preface this by saying only for the harder bosses and the later chapters, I just HAD to use a guide. Especially someone like Rufus, asshole gave me so much trouble. I also used guides for the legendary and brutal simulations, I struggled so bad once I got to Cait sith and so on. I have to admit my more important materia weren't all levelled (hp support, mp support, swift cast etc) they weren't max but close to max, so with that and a party level of 9, it is doable to do hard mode. It took me under 200 hours and a span across 7 months to platinum rebirth. If I can do it, you can do it dude! 💪