Walkthrough

1. Speak to Poliwrath, who is located east of the initial island at Sparkling Skylands, and hear its dilemma about a certain elevator.
2. Follow Poliwrath to the base of the elevator, and it will ask you to rebuild the broken ladder in the shaft and check out what's at the top.
3. Go ahead and use the nearby workbench to craft any kind of ladder pieces, then use them to rebuild the ladder.
4. Climb all the way to the top to see a non-functional elevator. Poliwrath will have an idea, so go back down and speak to it to learn of the next phase of the plan.

Walkthrough source: Game8.