After you go through Route 11 and pass through the captain's barricade, you go east to Route 12.
Explore Route 12
Go east to route 12. Hapu arrives and registers Mudsdale in your Ride Pager.
Go east and ride Mudsdale across the rocky ground.
Near the upper-right corner of the rocky ground, there is a Burn Heal.
To the east, there is another area of rocky ground. You can go south on the rocks to find a patch of grass. There is a narrow passage at the south end of that grass. After going through that narrow passage, you can go southwest to battle Rising Star Leilani, who has a level 33 Tirtouga. You get 1584 Pokédollars for winning.
South of Leilani, there is an Elixir.
Go northeast from Leilani, through another narrow passage, and you can have a double battle with Punk Pair Yoko and Lane. They have a level 32 Krokorok and a level 32 Pancham. You get 2048 Pokédollars for winning.
Go south, crossing some rocky ground with Mudsdale, and you can battle Rising Star Matthew. He has a level 33 Cranidos. You get 1584 Pokédollars for winning.
East of Matthew, there is a Hyper Potion.
There is more rocky ground south of Matthew. After you go across, go south and you find some grass. Walking around this grass, you can battle Scientist Jayson. He has a level 32 Porygon and a level 32 Magneton. You get 1536 Pokédollars for winning.
Within this circle of grass, on the right side, there is an X Attack.
From here, go west and you can battle Surfer Robert. He has a level 32 Remoraid and a level 32 Sandygast. You get 768 Pokédollars for winning.
Then you can go west for a brief trip to Blush Mountain.
Near the entrance of the area, you can battle Office Worker Shane. He has a level 32 Electrike and a level 32 Electabuzz. You get 1280 Pokédollars for winning.
In the grass behind Shane, there is a hidden Zinc.
To the west, there is a red truck. There is a Timer Ball behind it.
The fence behind the truck is a Poké Finder spot.
Southwest of the truck, there is a Sun Stone in the grass.
Inside of the Geothermal Power Plant building, talk to one of the Scientists in the Power Plant to get TM63 Embargo.
Talk to the guy in the bottom-left corner to get a Lure Ball.
Back to Route 12
Now leave the power plant building and go southeast to return to Route 12.
To the left, there is some rocky ground and some grass. You can go over the rocky ground if you want to avoid battling wild pokémon in the grass.
From here, go south to some grass. Samson will talk to you as you walk past, and you will also battle Swimmer Sara, who has a level 32 Starmie. You get 768 Pokédollars for winning.
Then go south through the grass and go southwest to find a hidden PP Up.
If you have defeated all the trainers in Route 12, you can talk to the Collector near the entrance to Blush Mountain to battle Collector Andrew. He has a level 35 Larvesta and a level 35 Pinsir. His Pinsir is holding a Buginium Z. You get 1120 Pokédollars for winning. Afterward, Andrew gives you TM82 Dragon Tail.
Then go east down the ramp to Ula'ula Beach.
At the rightmost side of the beach, there are some berries under the tree.
East of the tree, there is a hidden Big Pearl.
There is a police officer to the left. South of the officer, there is a hidden Pearl.
To the east, check the sparkle to read a letter in a bottle. The trainer is in Malie City Outer Cape, in the northeast corner. When you talk to him, you can battle him. He is Rising Star Nainoa. He has a level 29 Delibird and a level 28 Mudbray. You get 1344 Pokédollars for winning. Afterward, Nainoa gives you a Pearl String.
Back in Ula'ula Beach, to the left of the entrance of the beach, there is a hidden Dive Ball.
South of that, there is a hidden Pearl.
West of that, there is a hidden Big Pearl.
At the west end of the beach, there is a Revive.
There are no more items to find in Ula'ula Beach, so when you are ready, go north to return to Route 12, and go west from there to enter Route 13.
When you go into Route 13, there will be a cutscene. During the cutscene, Hau gives you a Max Potion.
There is nothing to find in the motel except a vending machine and a lonely Stufful.
Go west from the motel to find an oasis. There is a Moon Stone to the right of the water.
To the north, there is Haina Desert, but it is blocked by a captain's barricade right now. The old man southeast of the barricade will tell you that if you want to get through the maze in Haina Desert, look at the stone stacks. He says the answer is 2-1-4-3.
In the trailer west of the path to Haina Desert, there is a Punk Guy who asks if you want to battle. If you say yes, he gives you TM12 Taunt, but doesn't actually battle you.
South of the oasis, there is a ledge where you can do some fishing. There is a Guard Spec. on the right side of that ledge.
Go west to reach Tapu Village.