Thank you for that very informative reply. I understood most of it (sorta) and I've already done a lot of hex searching and relative searching without any luck. Right now I'm trying to use an emulator and Cheat Engine (which seems to have a debugger) to find the data. I've already found the data in memory and I can use Cheat Engine to set breakpoints and maybe trace the data though I'm not quite sure how it works.
This is where I'm at:
That 4d that is highlighted in green is the monsters HP and other stats follow shortly after that.
And is it possible the data would not show up when I look at the contents of the disk? Like hidden files or something?
Another thing I was wondering was how to re-insert any modified files back into the ISO. I used to use CDMage for psx isos but it doesn't work for ps2.