Hammerlocke Gym

Gym Mission
The eighth and final Pokemon Gym in both Pokemon Sword & Shield is found in Hammerlocke, and its a Dragon Type Gym. The Mission for this Pokemon Gym is relatively simple, as all you must do is defeat three trainers the Gym Leader personally taught himself. These battles, however, will be double battles, and all must be defeated consecutively in order to advance to the Gym Stadium.

Gym Trainer Sebastian: Level 45, Level 45 Sliggoo
Gym Trainer Camilla: Level 45 Ninetales, Level 45 Turtonator
Gym Trainer Aria: Level 45 Abomasnow, Level 45 Hakamo-o

Gym Stadium
Gym Stadium
After defeating the Mission, you will go on to face the Gym Leader, Raihan. Like the Pokemon Gym, he is a Dragon Type Trainer. He has four different Pokemon, and the final one he'll send into battle, Duraludon, will have the ability to Gigantamax.

Gym Leader Raihan: Level 46 Gigalith, Level 47 Flygon, Level 46 Sandaconda, Level 48 Duraludon

By defeating Raihan, you will earn the Dragon Badge. With it, you will have the ability to catch Pokemon up to Level 100. You will also receive TM99 (Breaking Swipe) and the Dragon Uniform. After defeating Raihan, you will have earned all eight Galar Region Gym Badges and will be able to participate in the Champion Cup in hopes of becoming the next Galar Region Champion.