Location in Johto
Mt. Mortar is one of the largest caves you have to explore in "Pokemon Crystal." You can enter the cave in one of three different locations, all located along Route 42. If you are far away from Route 42, select a Flying Type Pokemon and take the fast way there by flying to Mahogany Town. Once you arrive in Mahogany Town, hop on your bicycle and head straight west. You can't miss the three matching entrances.
Fighting Master Background
According to the Fighting Master himself, his Dojo was once a Pokemon Gym, but after Sabrina and her girls from the other Saffron Pokemon Gym defeated him and his fellow black belts in combat, his building's Gym status was revoked. After a stint running the Dojo, he decided to travel to Mt. Mortar to further improve his abilities as a Pokemon trainer.
Inside the Cave
To find the Fighting Master quickly, select the middle of the three entrances to the cave. Once inside, you will find yourself surrounded by water. Select a Water Type Pokemon and use the "Surf" technique to travel across the water until you reach a waterfall. Use the "Waterfall" technique to scale the cascading heights. From here you will travel in a continuing downward slope until you reach the bottom level of Mt. Mortar, where the Fighting Master waits.
Fighting the Master
As soon as you enter the Fighting Master's line of sight, he will challenge you to a Pokemon battle. Beware: He is an extremely talented Pokemon trainer with two fearsome Fighting Type Pokemon at his disposal, a Hitmonlee and a Hitmonchan. If you have any available, bring Psychic Type Pokemon to do battle against his two Fighting Type behemoths. If you succeed in defeating the Fighting Master, he will reward you with a Tyrougue, a very rare Pokemon specimen.