Challenge accepted.
Superhuman Tier
Vincent
Vincent is the most powerful protagonist in the series who isn't literally a god. He is Chaos, and single handedly defeated Omega WEAPON.
Layle (Empowered by Crystal Reactor)
He's basically a Green Lantern level superhero in this form.
Enhanced Human Tier
Zack
An enhanced SOLDIER. Far exceeds the limits of normal humans. Borderline superhuman.
Class Zero
Enhanced through Fal'Cie Arecia Al-Rashia's power, on top of the Vermilion Crystal's power. Can become l'Cie, which put them at borderline superhuman.
Layle
As a Crystal Bearer, is magic ability is far higher than a normal human's.
Wol
Seems pretty super. I don't know much about him yet.
Peak Human Tier
Ceodore
Possibly enhanced by his quarter Lunarian blood, but probably not by much.
Yuna
Peak human who has reached the heights of mortal magic ability.
Crystal Chronicles Hero
Normal peak human adventurer.
Yuri
Normal peak human boy.
Echoes of Time Hero
Normal peak human adventurer.
The Turks
Highly trained peak humans.
Ramza
Peak human soldier. No special abilities.
Marche
Peak human. No special abilities.
Luso
Peak human. No special abilities.
Benjamin
Peak human adventurer.
Sumo
Peak human gladiator.
Brandt
Peak human. Possibly enhanced by crystal.
Sol
Peak human. Possibly enhanced by crystal.
Rain
Peak human soldier. Story unfinished.
Prettz
Peak human adventurer.
The Explorer
Peak human equipped with Crystallizer.
Normal Human Tier
Leo
A King. No evidence of above average physical ability.
Mira
Daughter of the Dark Lord. No evidence of above average physical ability.
Aki Ross
Normal scientist.
Ai and Yu
Normal kids.
Tyro
Normal kid scholar.
Chocobo Tier
Chocobo
I think that's most or all of them. It's hard to keep track of the small mobile titles.