SQUEAKYREAPER'S PROFILE

If you have an ATB system, or any reasonably slow paced real time battle system in place, give enemy boss monsters some tells. Whether it's a consistent pattern of actions, your characters going "The enemy is charging up!", or them glowing blue, make the player know that the enemy is about to do something big.

Your status effects may have a weaker effect against bosses, or lower duration, but when that tell comes up you have to hit them with something. Perhaps you have simple "attack down" effects, or a blind to lower accuracy, or a silence to stop it entirely. The duration of the debuff would be shorter, but your player would be able to notice the effect it has on the enemy and would feel rewarded for saving that ace.

E: Avoid allowing your players to chain status an enemy to death, unless you can still manage to throw some sort of fair difficulty their way while doing this. If your Sleep duration is long enough that it will come back up again in time for you to use it on your enemy before they wake up, your boss fight becomes more akin to a pinata fight. Shorter duration means that spamming effects won't be as effective as timing them.

Could have probably finished it before the solar avatar came out. It gets to the point where you can just nuke everything with shooting stars. Holding back was getting me killed, though.