Emperor Mateus can transform into Emperor of Hell.
Kuja can go into Trance mode.
Very Important Condition
We are not going by Final Fantasy standards in terms of how much damage one antagonist can take. If we were, the Emperor would be one shot by Kuja because of how FF2's damage system was set up. We're going off what you guys think based on hype and personal beliefs.
The following are very important facts to consider before voting.
Emperor Mateus (before turning into the Emperor of Hell) has the ability to summon a raging cyclone, and has. This very cyclone he summoned and controlled destroyed many towns, much like Kefka's judgement beam after he ascended into God-hood.
After Emperor Mateus is defeated, he purposely goes to Hell and defeats Satan, thus becoming the Emperor of Hell. After he decends? into Hell, he sets up his new thrown titled Pandemonium Castle on top of Palamecia.
As one would expect of the game's primary villain, Kuja is shown to be an exceptional mage. He can create Black Mages from mist using machinery and magic, and even with no outside help can summon Mistodons. He is capable of controlling monsters as well, and is shown to control an army of Silver Dragons led by the Nova Dragon, as well as the monster Deathguise that attacks Zidane's party in the Crystal World. Kuja is also largely immune to injury - even the Dragon King Bahamut's attack only barely succeeds in drawing blood from him. It is also shown that even when not in Trance, Kuja is capable of casting the extremely powerful Flare Star. This makes him one of the most powerful, if not the most powerful, Black Magic practitioners in FFIX, even before he gained the ultimate power of Trance.
After entering Trance, Kuja's power increases exponentially. He knows the strongest spells of the game including Curaga, Meteor, Holy and Flare, and his strongest spell Flare Star is potentially lethal to the entire party. He is able to completely destroy Terra with Ultima, and even defeats the party with it. When Kuja casts Ultima against the party, no damage is displayed as being taken but the battle instantly ends, so it is physically impossible to survive the spell.
In your opinion, how would this battle play out?
Depending on your judgement, it may turn into a two-versus-two battle in the end.