Below is a guide on the locations of the 3 Digletts in the Warm-Up Tunnel.
1. On the left side just past the entrance to the Training Lowlands
2. From the previous Diglett, continue deeper in the tunnel until the path forks. The Diglett will be behind the two smaller sized rocks.
3. Just outside the tunnel to the right before entering Potbottom Desert
Click here for the next guide on the locations of the Digletts in Brawler’s Cave!