How do you think they got their "bad breath" attack? :p

So did I, and if I remember correctly that is how it was spelled in one of the games.

I think you mean FF6.

Well, there's not really "levels" per se. You just increase each individual stat on it's own through use. So, if a character gets his ass kicked in battle, if he's still alive at the end, he'll probably get an HP boost and an Endurance boost.

The thing with the Death Riders is that they seem to do a constant amount of damage regardless of how much armor you're wearing or how high a character's natural defense stat is. Example: my Gus had an endurance stat of 99, all of the Genji Armor and about 5,000 HP, and a Death Rider was still capable of taking him down in about two rounds. They'd actually do more damage to Gus than to Firion or Leon, who had significantly lower defense and about half as many HP. I figure that maybe they're programmed to do a half-assed "Demi" effect where they sap 50% of your Max HP instead of 50% of your Current HP. Either way, they're lame as hell.

FF3(Nes) Bahamut. You can fight him but cannot kill as he get healed back up to 65000 hp after each turn.

Then kill him in one turn, duh.