Originally posted by onajourney
Does this unlock all of the trophies in the game?
My guess would be no. Unlike "save sets", "Platinum saves" signify the uploaded save has already unlocked the Platinum, which would mean for instance all story missions and side missions involving a trophy are done. Since there's no chapter replay, you couldn't get those again with this save unless this save is different than what's normally meant by Platinum saves.
Depending upon the game and how trophies are triggered in it, you might be able to pop some trophies related to things like doing some action a certain number of times (even if the save is already well over that number, doing it one more time could unlock it), or if there are more collectibles in the game than needed for a trophy than if there are collectibles left on the map you might be able to pop those trophies. What's more likely would be some miscellaneous combat or other trophies, and here you'd be using an end-game character with end-game gear.