From Bulbapedia, the community-driven Pokémon encyclopedia.
The Underground Man (Japanese: ちかおじさん Underground Man) lives in Eterna City in a house next door to the Pokémon Center. He is the father of Byron and grandfather of Roark.
In the games
When players first meets him, he gives them the Explorer Kit. The other NPCs in his house describe various aspects of exploring the Sinnoh Underground.
He also gives a series of tasks, each with various rewards when they are completed:
| Use the Explorer Kit and go to The Underground
|| Move Trap (Up), Bubble Trap, Leaf Trap
| Dig something out of the wall
|| Prism Sphere 1, Red Sphere 1, Blue Sphere 1
| Plant a Sphere in the ground
|| Digger Drill
| Dig a Secret Base
|| Plain Table, Wooden Chair, Small Bookshelf, Buneary Doll
| Decorate a Secret Base
|| Doll of your Starter (Turtwig, Chimchar or Piplup)
| Capture a flag from another player's Secret Base
|| Bronze flag, ability to remove three boulders, Base Upgrade (Up to 12 Decorations), Pretty Gem
| Capture three flags from another player's Secret Base
|| Silver flag, ability to remove two more boulders, Base Upgrade (Up to 15 Decorations), Shiny Gem
| Capture ten flags from another player's Secret Base
|| Gold flag, ability to remove five more boulders, Mystic Gem, and a radar that shows the locations
of treasure, buried spheres and traps for the whole underground map.
| Capture fifty flags from another player's Secret Base
|| Platinum flag, ability to remove all boulders, Glitter Gem, and a star on the Trainer Card.
In the anime
The Underground Man first appeared in A Grass Menagerie! while Team Rocket was exploring the Sinnoh Underground. He convinced Jessie, James and Meowth to dig up spheres and shards for him from the Underground and fed them as a way of thanks. However, while they ate, he fled with the treasures.
In the manga
In the Pokémon Adventures manga
The Underground Man in Pokémon Adventures
The Underground Man first appears in Double Trouble with Dialga and Palkia I, where he and Byron were digging underground with the Explorer Kit to avoid Team Galactic from tracking the Sinnoh Gym Leaders. In the next chapter, he suffered the effects from the distortion of time and space caused by Dialga and Palkia battling. In Double Trouble with Dialga and Palkia VI, the Underground Man along with Byron, Professor Rowan and Sir Berlitz escape from the underground.
|| Dugtrio (×3)
| The Underground Man uses these three Dugtrio to help him dig underground. While digging, they were suffering the effects from the distortion of time and space caused by Dialga and Palkia battling.
None of their moves are known.
|| Double Trouble with Dialga and Palkia I