Castelia City

Immediately when you enter, go south. In this little pier thing is a guy who will give you an evolutionary stone. If you pick Pansage, you get a Leaf Stone, Pansear, you get a Fire Stone, and Panpour, you get a Water Stone. DO NOT evolve your monkey until it has reached Lv. 22, where it learns a really powerful move. Trust me. Anyway, let's go to the Pokemon Center to the west. The guy in it will give you items based on how many people you've traded with. Now, explore Castelia City heading left. In the Battle Company, just to the left of the Pokemon Center, are a bunch of people to battle. But the prize is the Exp. Share, which will help your training a lot, so definitely get it. When you get there, a guy will go on the elevator. Go to the 47th floor. There's a Male Clerk with a Timburr Lv. 19, and a Female Clerk with a Herdier Lv. 19. Talk to the guy near her and he'll give you 3 Quick Balls and 3 Timer Balls. The Scientist has a Roggenrola Lv. 19, and he likes to use an X Sp. Def. Then there is a Female Clerk to his left who has a Petilil Lv. 18 and a Cottonee Lv. 18. You can pick up a Revive next to her. To the right of the room is a Male Clerk who has 3 Basculin Lv. 17. Talk to the Scientist and he'll give you a Scope Lens. On the 55th Floor there is a Hyper Potion south of the elevator. To your left there is a Male Clerk with a Woobat Lv. 20. Then there is a Scientist with a Muuna Lv. 20 who should start the battle with an X Special. At the bottom of the room is a Scientist with a Sewaddle Lv. 20 and he uses a Dire Hit. Now there is another Male Clerk who has a Pansear, Pansage, and Panpour, all Lv. 19. Then you have to take on the boss janitor dude. He has a Trubbish Lv. 20 and a Minccino Lv. 20. After you beat him he gives you an Exp. Share. Well, that took a while.
In the Passerby Analytic HQ, the scientist guy will appoint you as statistician. Then, as you're leaving, a girl will come up to you. She'll ask you to complete some questionnaires, 8 in all. These will broadcast to fellow statisticians, and if you answer all 8, you'll get a Fresh Water.
Go up the alleyway to the left and you'll see the Gym. Walk up to it and Cheren will come out, bumping into you. He tells you that Bianca's Muuna has been taken by Team Plasma! Don't worry, we'll get these guys later. Let's explore the city! The building on the left is totally empty (but mark this spot-you'll be back here soon enough). Head north and you'll get to a central plaza thingy. Talk to the dancer and he'll battle you with a Pansage Lv. 21. He'll ask you to look for other dancers. OK, we'll do that in a little bit. See the vending machines to the north? They sell Fresh Waters, Soda Pops, and Lemonades. Buy about 10+ Lemonades, because they are quite useful. Now go to the alleyway just to the right of the one with the Gym. You'll see two dudes smirking. ?? Go farther up and a dude will jump from behind a dumpster. AAAAAA! But he makes it cool by giving you TM70 Flash. Oh, and don't forget that dancer. He has a Panpour Lv. 21. He'll leave after you talk to him. Also, there is a cafe with nothing of interest.
Go to Mode Street, right of the Battle Company. Whoa, look at all those people! There is an ice cream stand where you can get Casteliacones, but only on Tuesday, and only once a day, I think. Then there is a studio. Talk to the clown and he will ask to see a type of Pokemon. He'll reward you with berries. That's all, so head back outside. Then go up and back to the central plaza. Go to the alley on the far right. The first thing you'll notice is a building on the left. The woman in it will massage your Pokemon, so if you have a Woobat, have her massage it, because Woobat evolves at a high friendship level. Up the elevator is not much, so head back outside. Then, down on the right, is the Game Freak Building. If you have Celebi (obtained by the Relocator-I'll cover that in a sec), the little boy will turn into a Zoroa! It will be Lv. 10, always Female. If you don't have Celebi, the little girl will show you a pic of Zoroa for your Pokedex. Go up the elevator and the blue-harded dude at the table to the south will turn on the Team Rocket music! SWEET! However, I think that's later in the game. Anyway, here's the dudes from Game Freak, chillin' like always. Nothing of importance here, so head out. Nothing else on the streets except for North Castelia (we'll get that after the Gym).
Let's check out the piers! The pier to the far left, by the gate to Skyarrow Bridge, we already covered. The one by the Pokemon Center has absolutely zilch for this point in the game, so head to the one by the Battle Company. You see Bianca and Iris. Then a Plasma Grunt runs up, and runs off. There's the last dancer with a Pansear Lv. 21. Next, go to the west of the city. Burgh says the Grunts are by the Gym. He one you'll have to fight has two Sandile Lv. 17. They'll go into the building. When you go in too, you see Ghetsis with 2 other sages! Yikes! They'll leave, and Iris will give you a Yache Berry. Pick up the Smoke Ball before you leave. You can challenge the Gym now, but if you got the Liberty Pass, head the the far left pier so you can get Victini!
GYM
Get your Fresh Water from the dude you see when you get in. Now for the puzzle.
-Go through the honey to the north and step on the switch.
-Battle the clown with a Sewaddle and a Venipede, both Lv. 20.
-Step on the switch to the left. -Go through the honey by the clown.
-If you want to battle a clown with a Sewaddle Lv. 20 and a Dwebble Lv. 20, step on the switch.
-Step on all 3 switches (1 on right on 2 on the left).
-Go through the honey to the north of the clown you just fought (or didn't) and step on the switch.
-Go west, then north and through the honey, battle the clown with a Venipede Lv. 20 and a Sewaddle Lv. 20, then hit the switch.
-Go south, through two honeys, and don't step on the switch (unless you want to battle a clown with a Sewaddle Lv. 21).
-Go north, above the switch with a clown, and hit the last switch.
Feel free to heal up, as the puzzle will stay solved. Then, when you're ready, go through the last gate and battle Burgh! He has a: Whirlipede Lv. 21, Dwebble Lv. 21, and a Leavanny Lv. 23. All of his team is weak to Fire moves (except for Dwebble, who is weak to Water-but your best move should kill it in about 2 hits). After you beat him, you get the Insect Badge, and TM76 Struggle Bug.
After you get out of the Gym, Bianca will call you on the Xtransceiver. She wants to battle you on Route 4. We'll haed that way after we check out North Castelia. Heal up and go north.
Now let's check out northern Castelia. The dancer dude in the middle will give you an Amulet Coin. Head north now. There are two buildings. The one on the left has the Name Rater and the Feeling Reader. On the 11th floor is the dude who will unlock the Relocater. Just answer "Everyone Happy" then "Simple Connection" and the Relocater is unlocked. The clown will open an item currently unreleased, so don't worry about him. Now, let me explain the Relocator. Well, there's not much to explain. Go to the menu (the one with your save file) and scroll down until you see 'Relocator'. Click on that and you'll find the instructions. The Pokemon that can be transferred are the shiny Raikou, the shiny Entei, the shiny Suicune, Celebi, and the currently unreleased Lock Capsule. You'll need two DSs, just to let you know.
The building on the right has a dude in front of the elevator. Just talk to him, then go up. This floor has a lot of people speaking different languages. One of the girls in the bottom-right will give you TM45 Attract. That's all here. Head to Route 4!
GO TO ROUTE 4