Gym leaders. What are they, and why are they important in your Pokémon journey?

Gym leaders are people who give out badges(not for free, of course!). However, you must defeat them first BEFORE you can get the badge. Each badge has different abilities, such as the Boulder Badge allows your Pokémon to get stronger and the Cascade Badge allows Pokémon up to L30 obey. They are important because you need badges to get to Victory Road, the power of the badge lets you use certain HMs, and Pokémon will obey you. For example, you have a L56 Charizard and you have yet to get the Marsh Badge. The Marsh Badge allows Pokémon up to L70 obey, and since your Charizard is L56 and you don't have the Marsh Badge, the Charizard won't listen to you.

Each gym leader has their own separate page. Click on their names to look at their profile.

Brock
Misty
Lt. Surge
Erika
Sabrina
Koga
Blaine
Giovanni

After you defeat those eight gym leaders, you have the right to enter Victory Road. Victory Road leads to Indigo Plateau, where the Elite Four resides. The Elite Four are four powerful trainers(duh:) who have strong Pokémon with levels 50-65(I believe the lowest is Bruno's L53 Onix and the highest is Lance's L62 Dragonite!).

Elite Four

Once you've bested all of them, the last person you have to defeat is none other than your rival, Gary. Gary's lowest level Pokémon is his Alakazam(L59) and his highest is L65 Blastoise/Charizard/Venusaur. His Pokémon all are in the L55-L65 range.

Gary

When you have bested everyone, then you have the permission to enter the Unknown Dungeon and catch Mewtwo. =)