The first thing you’ll find in the Desert Resort (most of the things, even) is a battle.

Battle: PKMN Ranger Jaden (1380 Poke, Rawst Berry)
Opponent: Darumaka Lv 23

Watch out for the Fire Punch on Jaden’s Darumaka, it stings a -lot-.  Happily, he’ll give you a Rawst berry after the battle, so if you must, you can use that to sooth any singed hide.

In a pit to the West of Jaden, you’ll find a Stardust, which is a somewhat valuable selling item.  Keep going and duck into the cove in the wall South of you to grab a Green Shard, shortly after which you’ll encounter the West edge of the Resort.  Head one screen North and return to the East, up and down slopes, and you’ll find yourself at the East wall.  Putter North again across a sandpit to grab a Yellow Shard, then head West on the thin spit of light sand there.  Stop where it turns and the Ranger here will eventually run into you, prompting another battle.

Battle: PKMN Ranger Anja (1380 Poke, Rawst Berry)
Opponent: Magby Lv 23

Anja’s Magby not only has Flame Body, making it likely to inflict a burn, it also packs Flame Burst, which is fairly strong (but thankfully not burn-inflicting itself).  She does give you a Rawst Berry after the battle, but that may well be too late with her Magby’s powerful main attack.

After dealing with the second Ranger, take a short detour to the sunglasses-wearing man in the sandpit North of you to pick up a Soft Sand, useful for any Ground types you add to your team, or anything else that likes to use Earthquake (Hint: That’s practically everything.).