As soon as you arrive in the the city where the third gym is located, you will notice how different it looks from the norm as almost all of the city is indoors. With the place full of electricity running everything, it seems fitting that the gym leader would be an Electric type, not to mention the name Wattson kind of hints at it as well.
Starter wise, those who picked Torchic and have evolved it to the point of having fighting type moves would be in the best boat, as both Fighting and Fire will be super effective again the Electric/Steel dual type that will be found often here. If you have been able to find any, Ground type movies will be the most effective of all throughout the gym. The gym itself is pretty straight forward as you must step on switches to move the electric fences that block your way. Eventually you will get past and make your way to Wattson.
Below are the list of Trainers that players will get to meet in the Mauville City Gym and the Pokemon that they will use:
-Magnemite – Level 16 (Electric/Steel)
-Electrike – Level 16 (Electric)
-Electrike – Level 17 (Electric)
-Meditite – Level 19 (Fighting/Psychic)
-Voltorb – Level 15 (Electric)
-Voltorb – Level 17 (Electric)
-Magnemite – Level 19 (Electric/Steel)
-Voltorb – Level 19 (Electric)
-Magneton – Level 21 (Electric/Steel)
Rewards: Dynamo Badge, TM 72 Volt Switch