1. Get the Mach Bike: This is essential for navigating the route leading to the gym. You can obtain it from the Cycling Road.
2. Navigate to Slateport City: Use your Mach Bike to quickly get to Slateport City. You'll need to go through Route 120 and Route 121.
3. Enter the Slateport Gym: The Slateport Gym is easily recognizable, marked with a large electric sign and a distinct electric theme.
4. Challenge Wattson: Inside the gym, you'll have to navigate a series of electrified floors and defeat trainers before reaching Wattson.
5. Defeat Wattson: Wattson specializes in Electric-type Pokémon. Prepare a team with strong ground-type Pokemon like Groudon, Garchomp, or Swampert to counter his team.
Important Note: Before challenging Wattson, it's recommended to stock up on potions and other healing items, as the battles inside the gym can be challenging.
Once you defeat Wattson, you will receive the Thunder Badge and unlock the Electric TM. This will allow you to progress further in the game and face new challenges.