Squall would win on account that he's speedier with the gunblade. In a straight up, sword duel to the death, no magic/gf/materia, it could go either way. But Squall would have to stay on his toes, lest he be cleaved by Cloud's massive blade. And Cloud would have to be accurate with his swings, lest he be shot and slashed at the same time at the hands of Squall. To wrap it up, heres how the fight would probably go.
Squall get a few shots in, but is knocked down. Wounded, he uses Renzokuken, almost killing Cloud and cutting off his left arm. With the last of his strength, Cloud slashes Squall away, victorious. But he would be out of Hi-Potions, so he would die from his wounds. THE END
