With the exceotion of being shot in the head with little results, Could's abilities don't change. The only differences I recall are a change in wardrobe/attitude more swords, and a new limit break used to beat Sephiroth again (I call it neomnislash, as in neo+omnislash).
And another show of Cloud's strength. In the end of the game, Cloud lifts Tifa up onto a ledge. He does this with one arm; the other was holding Tifa. Let's face it, with breasts that big, no way Tifa's a lightweight. Cloud is strong.