In diamond, is there a pokemon after Mesprit that requires the masterball?

Once you beat it, there will be a secret path that will be cleared (I haven't played it in a while, so I can't remember where, sorry) That you'll have to go through, then there will be a laberenth in a cave. Once you navigate your way through it, you will meat up with Giratina (I think that's his name) You'll need it THEN.