The Castelia Gym has undergone some major changes since its original days. There's now a whole ton of spider silk all over the place! Be sure to talk to Clyde as soon as you enter for a free Fresh Water.
- Once you're up at Burgh's room, you can either fight him right away, or take the whole to the side to leave and heal up, which might be helpful to you (it opens up a shortcut that will let you get right back up to him). Approach the front hole in the silk egg to get sucked in and taken up another layer. There's a Harlequin nearby with a Sewaddle L20 and another Sewaddle L20 on his team.
- Take him down, then head to the egg in the top-right corner. That'll take you over to a sealed egg, but as you approach it, another Harlequin will jump out of it, using a Combee L20 and a Swadloon L20.
- Take that silk down to the first floor and fight a third Harlequin, this one using a Sewaddle L19, a Dwebble L19, and a Combee L19.
- Now get sucked into the egg right by him, except from the other side, and you'll be taken up to yet another Harlequin, who uses a Dwebble L20 and a Swadloon L20.
- Enter the hole on the left side (at the angle) and you'll be taken up to Burgh's room!
Whenever you're ready, talk to Burgh and begin your fight for the third Gym Badge — the Insect Badge!
His Swadloon likes to use Protect, but otherwise it will attack with Struggle Bug or Razor Leaf. It may also slow you down with String Shot, which is something you'll want to counter by switching out after you take it down.Burgh can be either insanely easy or pretty darn difficult depending on who you started with. If you started with Tepig, you should have no problem taking down his band of Bug-type Pokemon. But with Oshawott's weakness to Grass-type attacks and Snivy's weakness to Bug-type attacks, you'll need to rely on your team members if you want to have the best shot against him. Most of his team has a huge weakness to Fire- and Flying-type attacks, though, so something like a Growlithe, Magby, Zubat/Golbat, Pidove, or even Woobat may be handy if you don't have Tepig.
The Dwebble is what can give you trouble, due to its Smack Down attack. Being a Bug/Rock-type Pokemon with a Rock-type attack, it has no weaknesses to Fire- or Flying-type attacks and is able to hit both types for super effective damage with Smack Down. It also likes to use Rock Polish to speed it up for the fight! Using a Water-type Pokemon is the way to go, or possibly even a Drilbur with Metal Claw if you happen to have one.
Lastly he uses Leavanny, which is a great Pokemon and his is no exception. It is very fast, hits hard with Razor Leaf, and can also use Struggle Bug (for marginal damage) to lower your Special-based attacks. If you're planning on using Special-based attacks against it, try to take it out sooner than later, otherwise they'll be weakened.
After beating Burgh, he'll give you the Insect Badge, which ensures traded Pokemon up to level 40 without question, plus he'll give you TM76 (Struggle Bug), a weak Bug-type attack that also has the effect of lowering the foe's Special Attack. It's not overly useful, but sometimes it can be a help if you spam it against a tough Pokemon that uses such attacks.
Take the hole to the left of Burgh to exit the Gym as a victor. Now it's time for you to heal up your Pokemon and then head on over to Route 4, where you'll continue your adventure!