By anyone else's standards, Tiamat, Catoblepas, and all the others are bosses. In any case, your argument doesn't work because Sphinxaur, the first of these, has its HP permanently set at 10000, while Red Giant, another boss in Ultimecia's castle, has HP set at 30000. That having been said, I will reiterate, one final time, that the vast majority of bosses have tremedously variable HP. An extreme example would be Abadon, whose HP can range anywhere from 510 to 17010.Originally Posted by Delta
Further, there are situations where regular enemies have set levels. For example, all encounters on the Island Closest to Hell have maxed levels. In most cases, of course, the enemies level up with the player.