First of all, use Tifa instead of Barret, her limit breaks are much better. Second of all, why is Barret's limit break level higher than Cloud's? I don't think I've ever seen that. Learn Cloud's limit breaks as fast as you possibly can, trust me you won't be sorry. Best way to do so: have Cloud level up Cover and Counter Attack materia, and make him Hyper for faster Limit Gauge build-up. You'll learn his limit breaks in no time.