Abherrant Alexander. His gimmick of hopping around the large stage, casting slow on you, and firing missiles on you is easily countered with a remedy and Haste. He still has the massive hitboxes and the blind-spots of Alexander, but a player is capable of simply running in and aggroing, especially with Regen placed up, making Abherrant Alexander a real punching bag. Compared to the other Abherrants, who hit you with new attacks that give you very little warning time, this is a huge breather.
Demonic Spiders: Liches with how they love casting the powerful Flare spell.
With enough Luck and a lot of Save Scumming, the player can forge a Thieves' Anklet accessory that absorbs up to ten percent of the damage dealt to foes to restore health and AP. AP management no longer becomes a thought, and with enough aggression the player will absorb more health than most enemies can deal.
Regen is very useful - especially if you give it the right mutations. It will usually heal more than Curaga, and if you are a Dark Knight, it will literally undo all of the damage you just dealt to yourself if you cast it before or after you use Darkness or Sacrifice.
Deflect is one of the most useful skills in the game. It not only animation cancels, but can parry an attack. It's far easier to time than other similar abilities like Wall, and if you're using swords, learning how to use deflect can mean the difference between wasting five minutes to rez or not.
Vampyrs, a real annoyance with how they constantly drain your HP on top of having a small hitbox.
Malboros can inflict a variety of status ailments on you with their breath as with other Final Fantasy titles. Since status ailments wear off after a short period of time, they're less dangerous than in other Final Fantasy titles though.
Scrappy Mechanic: The Custom Ability system is rather cumbersome to use, relies on getting lucky enough to get the Crystal Surge you want, and requires spending CP to buy a new ability. And if you want that ability to have a custom name, you have to rename it. Every.Time.
Bahamut is a real Wake-Up Call Boss in that he swaps between two stances like Phoenix, but unlike Phoenix will throw down a Megaflare that sucks you into it. What's more, when Bahamut is on the ground, he can walk in your direction, and will literally kick you like a football multiple times. Sure, it doesn't hurt as much, but he usually kicks you again before you can even recover.
Odin really, really punishes you for being overly aggressive; he will use Zantentsuken multiple times. And if you think just picking him off from range will work, if you're far away enough, he'll charge at you. Fortunately, you can cheese him back if you are fighting him in the area where you can get the Hallowed Bolts cataclysm. You need it.
