Where's Admant Orb?
In Mt. Coronet!
It is in a room behind a bit of water, you will see it while going up to the Spear Pillar but you will have to go back and choose a different route to get there unless you have the walk through walls cheat. It is in the same room as the Lustrous Orb so if you leave room for Dialga in your party then you can pretty much catch Palkia straight after you catch Dialga!!!
They aren't there. There is only a plate by a rock