Route 412
Route 412 is the densest pickup route recorded so far — six of its 9 recorded pickups have a capture showing the exact tile. Work the eastern ledges first; the fossil choice is one-time and the Everstone is easy to walk past.
The eastern ledges
Thick Club sits behind the first ledge drop. It is a Marowak item, so it is worth collecting even if you have no Cubone yet.
You are offered one of the two and cannot return for the other on this save. Jaw Fossil gives Tyrunt; Sail Fossil gives Amaura.
Timed. Talking to him starts a one-day countdown. He wants a drink — hand over a Lemonade, Fresh Water or Soda Pop before the day is out. Let it lapse and he leaves with both fossils. Buy the drink before you talk to him.
TMs on the route
TM37 Sandstorm is a field pickup. TM05 Roar is held by the Ace Trainer (F) and only changes hands after you beat her.
Held items worth the detour
Bright Powder and the Everstone are both on this route. The Everstone matters more than usual here — several evolution levels differ from vanilla Platinum.