Pokémon FireRed and LeafGreen/Viridian Gym

Viridian Gym
From the dock, Fly to Viridian City. The old man previously blocking the entrance has moved, and informs you that the Gym Leader has finally returned. Time to earn your final badge!

Once you enter, you'll see a small maze filled with Gym trainers. Technically you only need to face two of these trainers to face the Gym Leader, one Cool Trainer and a Black Belt both north in the room, but you should really face them all and get all that delicious XP!

Once you finish your battles, you will face the Gym Leader... It's Giovanni, Team Rocket's own leader! It seems that after you defeated at Silph Co., he has returned to Viridian to regroup, and is ready for a rematch with you!

Giovanni will no longer call upon his Kangaskhan, and has decided to focus upon his Ground type Pokemon. Expect to face a difficult battle, as all know Earthquake, and all will benefit from STAB.

Both Nido's have a decent chance to Poison your Pokemon by their Poison Sting move, or through their Poison Point ability. Expect a particularly fast Dugtrio that will be particularly annoying with Mud-Slap, decreasing your accuracy. Both Rhyhorns are slow but can be a threat if they unleash Rock Blast on you.

Water Pokemon will work wonders in this battle. Grass Pokemon will be useful against Dugtrio and both Rhyhorns, but Nidoking and Nidoqueen's Poison type will nullify any advantage that Grass types would usually get.

Once you defeat Giovanni, he will recognize that he still has a lot to learn, and vows to one day return. He awards you the Earth Badge, which makes all Pokemon obey you regardless of level. He also awards you TM26 Earthquake, the most powerful Ground move in the game. You have finally completed the Gym Challenges!

Before you leave, stand on the exact spot where Giovanni stood, and use Itemfinder. Your final reward for beating Giovanni is the Macho Brace, a held item that will double any EV's that your Pokemon gets from battle, but halves its speed.

Now it is time to leave Viridian City, and head to your final challenge: The Elite Four!!!