Does anyone want to test my theory???
Shinryu has 51000 MP. I want to see if he can be defeated by attacking his MP before attacking his HP. "Magic hammer" (blue magic learned from either biblos world one or drippy world 2) halves the MP of its target. Combining this with time magic "Quick" would let you use "magic hammer" 8 times in your first turn. After a little calculation it seems Shinryu would be left with 199 MP. (Still enough to kick your arse??????) After a couple more and the bastid wont be able to use nout but basic attacks (still pretty damn strong tho :S)
But ive never used "Magic hammer" and dont know if it would work on a boss or how high a success rate it has