How do you get to the middle entrance of mt motar?

To reach the middle entrance of Mt. Mortar, head towards the Pokémon League area in the Johto region. From the entrance of the cave, navigate through the surrounding terrain to find the path leading to the middle entrance. Make sure to have the necessary HMs like Surf or Rock Smash if required, depending on the route you take. Once you locate the entrance, you can explore the cave's interior for items and Pokémon.