Putting aside stupid things like being able to break the damage counter, Cloud and Squall would be in a tie.
Squall - He'd probably be the biggest challenge for Cloud. With many years of experience with a blade, Squall would be a very formidable opponent. He also has the gunblade, which can shoot Cloud from a distance, or inflict extra damage up close. But Cloud has meteor rain, so he also has distance on his side. Omnislash = Squall's final limit(name's right on the tip of my tongue)
Zidane - No contest. Zidane can steal all the potions he want, but Cloud would blow him away with an Omnislash. Zidane may be able to turn Super Saiyan, but he has a snowball's chance in hell of beating Cloud and his awesomeness.
Tidus - Whiny little prick. Cloud could just show him a picture of him kissing Yuna, and Tidus would cry himself to Zanarkand.
Serious answer: Tidus is a whiny little prick. Cloud obviously has the advantage over Tidus, since he was infused with mako. And Tidus is also inexperienced with everything he does, except cry and Blitz Ball.
If it wasn't so specific, then I'd say what Behold The Void said about Locke.
