To obtain the third badge in Pokémon Prism, you need to travel to the town where the third gym is located, which is the Tectonic Gym. Make sure to defeat the gym leader, who specializes in Rock-type Pokémon, by using effective counters like Water, Grass, Fighting, Ground, or Steel types. Additionally, be prepared for any trainers in the gym and ensure your Pokémon are leveled up to handle the challenges. After defeating the gym leader, you'll receive the badge and can continue your journey.
The third badge is in Goldenrod City.
the third badge in sapphire is at mauville city(north of slateport city)
Head to lavaridge town for your next badge.
In Vermilion city.
first you need to tell me which Pokemon game you are playing
The sixth badgeno actually it the third badge
if you are looking for the third gym badge i suggest Veilstone city.
Veilstone City
vermillon city
Its hard to say -.-
You get your 3rd badge in Veilstone city against Maylene.
it is Mauville gym