The Desert Resort is essentially a massive sandpit with many trainers, patches of encounter sand, huge dunes/hills, and a crumbling castle somewhere out in the middle.  Since there’s really no limiting terrain, the writer is assuming starting from the gate and going left all the way, moving one screen up and going right all the way, moving one screen up and going left all the way, and so on until the area is scoured- remember, healing is free at that hut back outside the entrance, and more EXP is always better than less, so unless you’re really terrified of the sand and trainers for whatever reason, dig out everything you can do here and do it.

In the true Desert Resort, the sand has a slightly wider array of denizens.  On top of the Sandile, Darumaka, Crustle, Scrafty, Maractus, and Sandshrew, you can also pick up one new and one old Pokemon.  Sigilyph is a strange Psychic/Flying pokemon with passable defenses, good speed, and somewhat better Special Attack.  It can have one of two abilities- Magic Guard, which keeps it from being damaged by anything not actually an attack, and Wonder Skin, which keeps status-effect-only moves from working half the time.  Sigilyph specializes in moves with odd effects, like Synchronoise (damage all pokemon that share a type with the target) or Gravity.  It does end up with some fairly powerful attacks and Cosmicpower to boot, so it’s worth considering for your team if you don’t mind its bizarre look.

The old pokemon here is Trapinch.  Trapinch eventually becomes Flygon, the original Dragon/Ground pokemon, which has less raw power than its younger sibling Garchomp, but a little more flexibility and some different uses.  If you’re really inclined for a power moves Flygon, you may want to keep it a Trapinch through level 67, as it learns things like Earth Power and Superpower in Trapinch form, rather than Vibrava and Flygon’s somewhat earlier Dragonbreath, Dragon Claw, and Dragon Tail.  Either way, something worth considering as long as you can handle the 4x Ice weakness.

Immediately North of the gate is a nurse- but she’s also a trainer, so the first time you talk to her, she’ll insist on a battle.

Battle: Nurse Mariah (880 Poke)
Opponent: Cleffa Lv 22

Once you’ve beaten Mariah’s Cleffa, she’s happy to heal your entire team- just as though you’d gone back to the rest house or even all the way back to the last Pokemon Center you visited (and wasn’t that a staggeringly long way back).  She will do so each time you talk to her after this, making her immensely useful for keeping your team intact while mucking about in the sand.  Leave her and ignore the thirsty martial artist to head West.