I don't think you can that any of him are normal humans when all of them have killed godlike creatures and survived attacks that would kill any of us easily. Cloud can cut buildings in half, Squall took a giant icicle through the chest and lived, Tidus can hold his breath underwater for like forever and hurl and kick a ball at great speeds while underwater.

In this fight Tidus would be the 1st to lose. He lacks the ability to summon and if the other two start off summoning then he loses right then and there. I think Squall might win this though. It's hard to say who is more powerful going off from story since Cloud has been expanded more than Squall and Squall theoretically could be just as powerful or possibly stronger. Also why no Zidane?