The Adamant Orb and Lustrous Orb are both in the same small cave chamber deep inside Mt. Coronet.
To reach them you will need to bring Pokémon that know the Hidden Moves Rock Climb, Strength, Surf, and Waterfall.
Getting the Orbs (Step-by-Step)
The signature Orbs of Dialga and Palkia are located deep within Mt. Coronet. They won’t be available until after you’ve defeated Leader Volkner in the Sunyshore City Gym and received the Beacon Badge from him.
To reach the cave chamber containing the Orbs, you will also need Pokémon in your party with the following HMs:
- Rock Climb
The entrance to Mt. Coronet that you want to use is northeast of Oreburgh City.
So Fly to the Oreburgh Pokémon Center and head north along the main road.
Take the stairs at the northern entrance to leave the city for Route 207.
Go down the small staircase leading to a pit, where there is a muddy slope in the middle of the north wall.
Ride your Bicycle in fourth gear to make it up the slope.
Take an immediate right into the canyon by the Honey Tree.
Travel all the way to the east until you come to Mt. Coronet’s entrance, and head inside.
Once you’re inside, use Surf to cross the small lake to the north.
On the other side of the water, walk over to the rocky wall and use Rock Climb to scale it, then head upstairs.
In the next room go north and take the left turn, ignoring the staircase.
Turn south and use Strength on the boulder in your path to push it further southward.
Push the boulder until you can head up the staircase and travel north along the elevated terrain.
Cross the bridge at the end heading west.
Then descend the nearby staircase, pass under the bridge you just crossed, and climb the two staircases to the north.
Cross another bridge to the east, then circle around to pass under that bridge as well.
Then you can climb the stairs in the northwest corner of the room.
Exit the area through the hole behind the cave painting that Team Galactic broke.
In this next area just ascend the two staircases leading to the next chamber.
Then head up the big staircase leading north.
As the pathway wraps around you’ll want to follow it going left.
Then turn southward and travel down the hallway to exit the cave.
Once you’re outside, head east.
Turn northward and follow the path all the way up.
Use Rock Climb on the rocky wall at the end of the path, but ignore the 2nd Rock Climb spot.
If you turn right after the first rocky wall then you should see another entrance to the cave.
Once you’re back inside, turn left and descend the staircase.
Use Surf at the lake here.
Then surf north toward the waterfall.
Use Waterfall to climb the falls, then go straight forward to enter the next cave.
This leads to a small chamber with two Poké Ball items in the top corners.
The Poké Ball on the right contains the Lustrous Orb, and the one on the left holds the Adamant Orb.
What Do These Orbs Do?
The Adamant Orb and Lustrous Orb are held items that are specific to Dialga and Palkia, respectively.
They boost moves of either Pokémon’s signature types by 20%.
The Adamant Orb
The Adamant Orb boosts Dialga’s Dragon-type and Steel-type moves by 20% each.
Dialga is built like a tank, but its slower Speed and Dragon/Steel typing make it a better defensive wall than an offensive sweeper.
This makes Leftovers a better item for Dialga to hold than the Adamant Orb in most cases, since that allows Dialga to replenish its HP while setting up trap and status moves like Stealth Rock and Toxic.
Alternatively, a Choice Scarf would help shore up Dialga’s Speed stat. That would do a better job of turning Dialga into a sweeper, rather than the Adamant Orb’s damage bonus would.
The Adamant Orb isn’t a bad item, but there are better ones for Dialga.
The Lustrous Orb
Palkia’s dizzying Attack and Special Attack stats, decent Speed, and Dragon/Water typing makes it a highly effective sweeper.
The Lustrous Orb is a fantastic item to use instead.
With no drawbacks to contend with, Palkia can come out swinging with a Spatial Rend/Draco Meteor or Surf/Hydro Pump that’s even more devastating than usual.
This is one of the best items Palkia can hold and is highly worth trying out.