Pokemon Black White Version 2 – Gym Challenge Series: Castelia City

Having completed everything in the sewers it is time to head over to Burgh's Bug-based Gym. You will find it on Gym Street, on the far Western side of town. Head Up along the street and into the first building on the right to get into the Gym itself. The suggested level for this is between 20 – 22. The highest you will see in this gym is Lv. 24 (Lv. 26 in Challenge Mode)

Cylde will greet you inside and explain that the theme of this gym is cocoons. He will also tell you that most will try to get the edge in battle by lowering your Pokemon's speed or boost their own. This can take some management to handle but for most of the battles it is nothing horrible.

You need to use the intricate webbing system stretching between cocoons to move through the different levels of the gym to reach up to Burgh who is at the very top of it. It is not too hard to figure out as you can somewhat trace the lines of thread, but that takes a lot more time. Start by heading straight into the first cocoon in front of you.

Congratulations, you can clean house in this gym. All you need is a good power Fire-type move and you will be moping the floor with every trainer that you encounter. While you have the occasional Dwebble, they are still weak to Fire. More things than not will simply burn in front of you.

You are in a tight spot. Everything has something of a bug move and most of a second type of grass. Those which have Rock-type are also Bug-type, putting your damage at normal. You can handle the grass types better, which are common, but you have the worry of the Bug-type attacks.

You are in a horrible spot. While normally Water-type and Bug-type do not care too much, much of what you are facing also has Grass-type which simply destroys Water-type. Only the Dwebble are fairly safe to square off against. If you have can a Pidove, or better, a Growlithe lead for this, you will take them all out no problem.

This will take you up a level to the second floor. Head over to the right. There you will encounter Harlequin Clarence, the first of four trainers found inside the gym:
Harlequin Clarence: 2 Pokemon
1 – Sewaddle Lv. 20 Bug/Grass
2 – Sewaddle Lv. 20 Bug/Grass

Now, head to the Right of Clarence and over to the next cocoon above you. You will get sucked in and pulled up to the next level. Head down and to the right once you exit, passing in front of the next cocoon. This will prompt Harlequin Jack to make his appearance and challenge you:
Harlequin Jack:
1 – Combee Lv. 20 Bug/Flying
2 – Swadloon Lv. 20 Bug/Grass

Head into the cocoon that Jack just came out of. It will take down to the ground floor, but in a different area then where you started. Head just a few steps to the right then turn upwards. This will prompt the third trainer in the gym to challenge you, Harlequin Gary.
Harlequin Gary:
1 – Sewaddle Lv. 20 Bug/Grass
2 – Dwebble Lv. 20 Bug/Rock
3 – Combee Lv. 20 Bug/Rock

Having dealt with Gary, go into the right-hand side entrance of the cocoon. It will take you back up to the second floor. Head down and to the left to find the final trainer, Harlequin Anders:
Harlequin Anders:
1 – Dwebble Lv. 20 Bug/Rock
2 – Swadloon Lv. 20 Bug/Grass

It is now time to go and face Burgh. If you team needs it, head back out of the gym and hit the Pokemon Center. It helps to be fully healed in case something goes wrong or Burgh gets a lucky shot in.

Burgh will brag plenty about his Pokemon than congratulate you on your work in the sewers with your rival. After that he will finally get around to challenging you for the Insect Badge:

Hyper Potions: 1
Swadloon Lv. 22 Bug/Grass
Ability: Leaf Guard
Moves: Razor Leaf, String Shot, Protect, Struggle Bug

The Swadloon can be annoying if it gets very lucky with Protect after it uses String Shot up to 6 times on a Pokemon. This will put this Pokemon as the forerunner in combat every turn. However, this Pokemon has horrible weakness to Flying and Fire-Type Attacks, as they can reliably take it out in a hit or two.

Dwebble Lv. 22 Bug/Rock
Ability: Sturdy
Moves: Smack Down, Faint Attack, Rock Polish, Struggle Bug

If there is one ability that can make Dwebble a little annoying, it is Sturdy. This ensure that it will survive the first hit. At this level it will not make a big difference beyond Dwebble will get an attack off even if you go first and hit it hard enough to KO it.

Leavanny Lv. 24 Bug/Grass
Ability: Swarm, Item: Sitrus Berry
Moves: Cut, String Shot, Razor Leaf, Struggle Bug

The Leavanny is the strongest Pokemon that Burgh has. Once this time comes up, it is the real fight. It is also holding a Sitrus Berry so it can restore health once it drops into the yellow range, if not red. It's ability, Swarm, amps up the power of Bug-type moves once the user is in the red. It is not a great ability, but it does make Struggle Bug a bit more dangerous if it gets used. It does have some good power behind but is it not that strong. It remains that Fire and Flying will carry the day against Leavanny.

Once you have taken down Burgh you will be rewarded with the Insect Badge and the TM for Struggle Bug, which can lower the target's Special Attack when the attack connects.