It's a decent strategy, but if you have pokemon like Giaratina and Salamance, you shouldn't have too much trouble against the opponent. it would be easier (time wise, money wise, and would keep Giratina's happiness up) to just sweep with them. Since you mentioned using Revive, I assume this is for in-game. (you can't use those type of items in wifi battles.)
-Protect loses accuracy when used repeatedly, so it wouldn't guarantee safety for Salamence.
-Salamence has high attack power, so having him just stall would be a waste of that attack power.
-Giratina has massive HP, so just using him as a target like that would be wasting his potential as well.
-Focus sash only activates when the holder is at full HP. A pokemon like Giratina is way to powerful to get OHKO'd by a lot of things, and definitely not from an in-game opponent.