The only reason he's recognized as first class is because he believes he is and therefore tells everyone he is. He was never actually a SOILDER 1st class. Zack Fair was. regardless, yes cloud knows how to use the buster blade(although it was never meant to be used.). And I agree link is just a kid who found a sword and doesn't know how to use it.
Sora from Kingdom Hearts is able to defeat Cloud and deflect his Omni-slash so I think Link can definitely defeat Cloud hands down. There is no way to tell how much Damage Link does with his Master Sword but come on, it's the Master Sword. The Master Sword was ranked the #1 best weapon in a video game for all of its abilities.