The trick is the GF abilities more than anything- prioritize stat junctions and any refine ability. Always have draw set and make sure you try to draw from every boss fight in case they have a GF, it can be easy to miss (I missed several my first playthrough). The GF summon abilities can be ignored other than maybe diabolos; he's very helpful for getting tonberry once you get the mobile garden and tonberry has some excellent refine abilities IIRC. I haven't played in years tho.I knew about the abilities but I didn't know about the T-Rex trick.
I think I just don't have the patience to experiment with that sort of thing which is why I never tried. That said, I am now extremely curious about what else I can break now that I know that.