At last, I had found the hex decimals (not really exectly) to make the main char (Cloud) invinsible in battle which the char will not take any damage and has unlimited MP. But however, the char needs to take a single hit before he change into invinsible mode. That's really annyoing me and I'm still searching the right decimal so that the char become invinsible as soon the battle start.
I even found out that the limit break of each chars can be swapped by changing the right hex decimals in Kernel2.bin (or kernel3.bin). When I'm in the process of trying to find the hex decimal so that my char become invinsible in battle, I found out something really interesting - as soon as the battle start or each time Cloud takes a single damage from the enemy, he will cast BEAST FLARE (Vincent 1st Limit Break) . I even accidently discover by randomly playing with the hex decimals that
each time Cloud take a single hits from the enemy, he will counter attack with his 1st Limit Break (Braver or Cross Slash) even though his Limit bar is not full.