User blog comment:Leolab/Siege Breakers Season, Battle 3: Guts (Berserk) vs Nightmare (Soul Calibur 3)/@comment-422690-20131017013103

So... here's my take:

I think Nightmare will win out over Guts. Since this is Guts before he gets the Berserker's Armor, it's Guts a a peak human against Nightmare as a demon. Guts will likely win against Nightmare in his normal form; they're both excellent swordsmen, but Guts is better. However, once Nightmare transforms into Night Terror - the equivalent of an Apostle entering their Apostle Form - the entire story changes. Guts tends to get tossed around by his opponents when they enter Apostle Form. Usually, he exploits their tendency to gloat to get in position to strike. SCIII Nightmare doesn't do that.

Essentially, I'm seeing this go down a similar way to Guts's first fight with Nosferatu Zodd - he's able to fight properly against his foe, but once they power up he's not going to be able to do too much.