You'll need to increase the humidity in Pokémon Pokopia early in your adventure to restore the Withered Wasteland and earn the right to explore other regions. Professor Tangrowth is a bit vague about ...
Once you make your home for the first time in Pokemon Pokopia and raise the Withered Wasteland's Environment Level to three, you can speak to Tangrowth to get a new task: to rebuild the crumbled ...