At Striaton City. There are three gym leaders, although you can only battle one depending on which starter you have. If you choose Tepig, then you will have to battle Cress who has a panpour and lillipup, if you choose Snivy you have to battle Chili who has a pansear and lillipup, and if you choose Oshawatt you have to battle Cilan who has a pansage and lillpup.
Driftveil City. Gym Leader Clay!
Cheren
pass the 5th gym leader
To the musuem. The museum in in the town with the first gym leader.
In Pokemon Red/Blue/Yellow and Pokemon FireRed/LeafGreen, the Celadon City Gym Badge is required to use Strength. Gym Leader Erika holds this badge.In Pokemon Gold/Silver/Crystal and Pokemon HeartGold/SoulSilver, the Goldenrod City Gym Badge is required to use Strength. Gym Leader Whitney holds this badge.In Pokemon Ruby/Sapphire/Emerald, the Lavaridge Town Gym Badge is required to use Strength. Gym Leader Flannery holds this badge.In Pokemon Diamond/Pearl/Platinum, the Canalave City Gym Badge is required to use Strength. Gym Leader Byron holds this badge.In Pokemon Black/White and Pokemon Black 2/White 2, Gym Badges are not required to use HMs.
Brock is the first gym leader in pewter city.
in the museum
The first gym in Pokemon diamond is in Oreburgh City
You kill the Gym Leader's Pokemon with your Tepig.
You Cant
Herdier and Watchog.
Driftveil City. Gym Leader Clay!
The 8th gym leader is Drayden, who uses Dragon-type Pokemon. You face him in Opelucid City.
Lenora, the second gym leader, is found in her gym AKA the museum in Nacrene City.
From the 1st gym leader
druddigon, fraxure and a haxorus
Have a water ice or grass pokemon.