Olivia's letter says that she will meet you in the Ruins of Life, so you go through Memorial Hill to get there.
Go Through Memorial Hill
Go to the right, up a short set of stairs. There is a hidden Heal Powder on the grave to the right of the girl and the Rockruff.
Go to the right from there and follow the path, and you can battle Gentleman Smith. He has a level 23 Umbreon. He can use a Full Restore during the battle. You get 4600 Pokédollars for winning.
Go to the left, and the path will split. You can keep going to the left and check on the grave to get an Adrenaline Orb.
South of there, you can battle Preschooler Liam. He has a level 21 Jigglypuff and a level 22 Ledian. You get 264 Pokédollars for winning.
To the right of the Preschooler, you find a Cleanse Tag.
Now go north and check in front of the upper-left grave to get a Super Repel.
Farther north, you can battle Madame Sayuri. She has a level 23 Comfey. You get 4600 Pokédollars for winning.
To the left of Sayuri, there is a hidden Revival Herb.
Go through the grass to the left and follow the path to find a Dusk Ball.
To the right, you can battle Punk Girl Melissa. She has a level 23 Ariados. You get 736 Pokédollars for winning.
Go southwest from the Punk Girl to find a Spell Tag in front of a grave.
Go southeast through the grass to find a path to the right of the trees. At the end of that path, you find a Hyper Potion.
Go back to the grass, then go south and you find some Aether Foundation people arguing with Team Skull. The Aether Foundation Chief asks you to fight on his behalf.
You battle a Team Skull Grunt that has a level 23 Raticate. You get 736 Pokédollars for winning. The Chief asks you to meet him at Hano Grand Resort after your trial.
Go east from where you battled the Team Skull Grunt, and you will reach Akala Outskirts.