After you defeat Flannery in the Lavaridge Gym, your Dad finally agrees to battle you in the Petalburg Gym.

Prepare

The Petalburg Gym is a Normal-type gym. Normal-type pokémon are only weak to Fighting-type attacks. Rock and Steel pokémon are strong against Normal-type attacks, and Ghost pokémon are immune to Normal-type attacks. However, several of the pokémon that you will encounter in this gym know Dark-type moves, which Ghost pokémon are weak to.

Some of the trainers have female Delcattys that can cause your male pokémon to become infatuated. Therefore, you might want to only send female or genderless pokémon into battle against these Delcattys, since they can't become infatuated with a female pokémon.

Battle Trainers

There are several different paths that you can take to the gym leader. You have to battle at least three trainers to reach him. Also, it is possible to battle all of the trainers in this gym by going back the way you came and taking different paths.

From the entrance to the gym, you can either go through the door on the left or the door on the right. If you enter the door on the left, you will be in the Speed Room. If you enter the door on the right, you will be in the Accuracy Room.

Speed Room

Ace Trainer Randall is in this room. He has a Delcatty. He uses an X Speed at the start of the battle, increasing Delcatty's speed by one stage.

After this battle, you can either go into the door on the left to enter the Zero Reduction Room or go into the door on the right to enter the Defense Room.

Accuracy Room

Ace Trainer Mary is in this room. She has a Delcatty. She uses an X Accuracy at the start of the battle, increasing Delcatty's accuracy by one stage.

After this battle, you can either go into the door on the left to enter the Defense Room or go into the door on the right to enter the Recovery Room.

Zero Reduction Room

Ace Trainer Parker is in this room. He has a Linoone. He uses a Guard Spec. at the start of the battle, preventing you from reducing Linoone's stats for five turns.

After this battle, you must go into the Strength Room.

Defense Room

Ace Trainer Lori is in this room. She has a Linoone. She uses an X Defense at the start of the battle, increasing Linoone's defense by one stage.

After this battle, you can either go into the door on the left to enter the Strength Room, or you can go into the door on the right to enter the One-Hit KO Room.

Recovery Room

Ace Trainer George is in this room. He has a Linoone. He uses healing items on his Linoone throughout the battle.

After this battle, you must go into the One-Hit KO Room.

Strength Room

Ace Trainer Jody is in this room. She has a Zangoose. She uses an X Attack at the start of the battle, increasing Zangoose's attack by one stage.

After this battle, go north to challenge the gym leader.

One-Hit KO Room

Ace Trainer Berke is in this room. He has a Zangoose. He uses a Dire Hit at the start of the battle, which increases Zangoose's chance of making a critical hit.

After this battle, go north to challenge the gym leader.

Norman

Norman has Vigoroth, and two Slakings.

The two Slakings have the ability Truant, which causes them to only attack on every other turn. You can use this to your advantage if any of your pokémon know Protect or Detect, because you can use Protect or Detect right after Slaking skips a turn, preventing any damage, and only attack when Slaking skips the turn.

The first Slaking knows Yawn, so it would be a good idea to plan to use at least two pokémon against it. That way, you can switch out your pokémon after Slaking has used Yawn, preventing it from falling asleep.

All three of Norman's pokémon know Retaliate, which is stronger if it is used on the turn after one of your pokémon faint. All three also know Feint Attack, a Dark-type attack.

After Your Win

After you get the Balance Badge, traded pokémon up to level 60 will obey you. You can now use Surf outside of battle.

Your Dad also gives you TM67 Retaliate.

You and Norman will go outside, where you meet Wally and his father. Wally's father gives you HM03 Surf. Your Dad says to visit Route 118. You'll automatically go with Wally to Mauville City, and Wally continues on to Route 118.

Before you go, visit the Mauville Pokémon Center. If you have a Diancie from a distribution event, there will be a cutscene in the Mauville Pokémon Center where you will receive the Mega Evolution stone, Diancite.

In the Mauville Pokémon Center, talk to the old guy to get some new O-Powers. If you talked to a red-haired guy, leave the Pokémon Center and go back in to find a blue-haired guy. Listen to his song (be sure to have the volume turned up) to get another O-Power.

Now that you have defeated your Dad, you can get an Amulet Coin from your Mom in Littleroot. The Amulet Coin increases the money that you win from trainer battles.

It will take a while to get to the next gym, which is a Flying-type gym.. But if you want to start preparing, bring some Rock, Electric, and Ice pokémon to start training.

You can explore many optional areas now, such as Route 105, 106, 107, 108, and 109. You can get to Route 105 by going southwest of Petalburg City, and you can get to Route 109 by going south from Slateport.

When you're ready to continue the storyline, be sure to teach Surf to one of your Pokémon, then go east from Mauville to Route 118.