Crimson from Digimon World 2. He brings two very strong Ultimates who both have obscene status effects. The first literally blocks your two strongest attacks from being used, while the other heavily debuffs Vaccine type Digimon (the most common team people usually join). And one of them has obscene defense to stop you from nuking him before they get rolling. And he comes after another decent boss prior and has a fucking nother boss after him.
The entirety of Data Domain literally 2-3 missions later is even worse. Where you have a gauntlet of like 7 bosses in a row, all of which are confusion themed. Its usually recommended to just do 2 or so, leave and then come back. Because they stay defeated, and the hour+ time loss is easier than the huge item loss you'll use trying to recover after each one. Made even worse by the fact that most of their Mons are fucking terrible and would be a joke without the Confusion hell.
And its a dungeon crawler, so its not like you are ever walking up to them topped off on health/mana. You are getting fucking dragged by Digimon that are only a step below them attacking you constantly while you desperately try to find the Floor Portal to go down. While also staving off your Tank running out of health/mana itself (an instant return to base with a huge item loss cost), while also dodging Bug Traps because if you get unlucky and its a Return Bug (which will send 0-3 Digimon back home and out of your team) you basically have to just give up. All of these things can be fixed with items, but you have an item limit so any Healing Disc means one less Bug Zapper or Drill Missile you might need to progress.
Honestly, every boss in the game could qualify after the first 3rd.
Crimson from Digimon World 2. He brings two very strong Ultimates who both have obscene status effects. The first literally blocks your two strongest attacks from being used, while the other heavily debuffs Vaccine type Digimon (the most common team people usually join). And one of them has obscene defense to stop you from nuking him before they get rolling. And he comes after another decent boss prior and has a fucking nother boss after him.
The entirety of Data Domain literally 2-3 missions later is even worse. Where you have a gauntlet of like 7 bosses in a row, all of which are confusion themed. Its usually recommended to just do 2 or so, leave and then come back. Because they stay defeated, and the hour+ time loss is easier than the huge item loss you'll use trying to recover after each one. Made even worse by the fact that most of their Mons are fucking terrible and would be a joke without the Confusion hell.
And its a dungeon crawler, so its not like you are ever walking up to them topped off on health/mana. You are getting fucking dragged by Digimon that are only a step below them attacking you constantly while you desperately try to find the Floor Portal to go down. While also staving off your Tank running out of health/mana itself (an instant return to base with a huge item loss cost), while also dodging Bug Traps because if you get unlucky and its a Return Bug (which will send 0-3 Digimon back home and out of your team) you basically have to just give up. All of these things can be fixed with items, but you have an item limit so any Healing Disc means one less Bug Zapper or Drill Missile you might need to progress.
Honestly, every boss in the game could qualify after the first 3rd.