So, after being confidant enough in my strategies, I actually attempted some of the level 99 special Nemeses fights. Only to find that they aren't actually what they show in there picture. I was confused for a little bit, but then, after doing some research, I found that the specially named ones are actually holiday special fights. For example, Be Mine; White Fox is actually a fight against a Level 99 Barras and Holly that was released on Valentine's Day, and just uses Mammon's picture to display on the Nemesis screen. They recently dropped an April Fool's Day fight as well (I think that one was about level 30).

These fights are fantastic, because in addition to mixing up the standard Nemesis system, they also drop Unearthly Buns, the best stat booster item in the game (each Unearthly Bun is essentially one of every other Bun combined).