Nyx from P3 wasn't that hard he was just really annoying. A lot of bosses from the Answer (P3's epilogue) really kicked my ass to point I had to stop playing for half a year. The thing that pissed me off about the answer is that it is on hard mode by default and there's no way to change it. I'm stuck on Erebus where my party, which usually does 200+ damage, does like 80 hit points with our Personas.
Ultimecia from FF8 also wasn't hard but was again annoying where you have to spend several minutes trying to get your desired party as she chose your party for you. Although it was always funny to see her pick your least used party members as she scales her level depending on the chosen party so she's level 11 while I'm level 97. Speaking of which, I beat Omega Weapon in one try; he wasn't that hard.
Ultimecia from FF8 also wasn't hard but was again annoying where you have to spend several minutes trying to get your desired party as she chose your party for you. Although it was always funny to see her pick your least used party members as she scales her level depending on the chosen party so she's level 11 while I'm level 97. Speaking of which, I beat Omega Weapon in one try; he wasn't that hard.