I arrived at the Pokemon Center by the entrance to the Rock Tunnel and I headed inside in order to heal my Pokemon. After healing them, I went back outside and trained my Pokemon in the tall grass by the stream that led to the Power Plant, then I went back to the Pokemon Center to swap Pokemon and I entered Rock Tunnel afterwards. I used Flash since it was completely dark inside and I moved around the first cavernous floor and I battled some wild Pokemon. As I moved around the next couple of floors, I battled some trainers and I also caught some wild Pokemon like Machop and Onix. I battled all the trainers inside the tunnel, then I exited the cave and battled a few more trainers north of Lavender Town.