This is a list of gym leaders with their pokemon information!

Roark

The first gym leader is Roark of Oreburgh City. He uses all rock types with rock type attacks. Beat him and get the coal badge and Tm-76, also you can use rock smash outside of battle.

Pokemon
Geodude-Level 12
Onix-Level 12
Cranidos-Level 14

Gardenia

The second gym leader is Gardenia of Eterna City. She uses all grass types. You must find the four gym trainers yourself before you can battle her. For beating her you get the forest badge and TM-80.

Pokemon
Cheribu-Level 19
Turtwig-Level 19
Roserade-Level 22

Meylene

The third gym leader is Meylene of Veilstone city.She uses fighting types, to get to her you must solve a maze. For beating her you get the cobal badge, you can also use fly outside of battle.

Pokemon
Meditite-Level 27
Machoke-Level 27
Lucario-Level 30

Crasher Wake

The fourth gym leader is Crasher Wake of Pastoria City. He uses water types and his puzzle is water related. When you beat him he gives you the fen badge and you can use Defog outside of battle

Pokemon
Gyarados-Level 27
Quagsire-Level 27
Floatzel-Level 30

Fatina

the fifth gym leader is Fatina of Hearthome City.She is a ghost trainer. To battle her you must find her by the Contest Hall.Upon defeat you get the relic badge and the ability to use surf outside of battle.

Pokemon
Drifblim-Level 32
Gengar-Level 34
Mismagius-Level 36

Byron

Byron of Canalave City is the sixth gym leader.You must use platforms and levers to get to him. He is a steel type user. You get the mine badge for deafeating him, you can also use strength outside of battle.

Pokemon
Bronzor-Level 36
Steeliz-Level 36
Bastiodon-Level 39

Candice

The seventh gym leader is Candice of Snowpoint City. She is an ice gym leader. Her gym puzzle is also snowy and icy. When she is defeated you recieve the glaceon badge and can use rock climb outside of battle

Pokemon
Snover-Level 38
Sneasel-Level 38
Medichan-Level 40
Abomasnow-Level 42

Volkner

the eighth gym leader, Volkner of Sunyshore City uses electric types.You create a path to him by pressing buttons that rotate the bridges. When deafeated he gives you the beacon badge, you can also use waterfall outside of battle.

Pokemon
Raichu-Level 46
Ambipom-Level 47
Octillery-Level 48
Luxray-Level 49

All 8

Now with all 8 badges you can head out to the victory road and then the elite four.