As soon as you move under the bridge, you're in Icirrus City! This city is pretty spread out so it's easy to miss something. Luckily, w'ere here to make sure that you don't! First, when you see the stairs leading up to the higher level, move up them, then head west over the white bridge
You'll be at the Pokemon Center . Head inside; heal your Pokemon and stock up on any items that you feel you may need. To the right of the Nurse's counter is a man that you can sell evolutionary stones to (eg. Fire Stone, Thunderstone etc.) as well as a variety of different items of value.
If you've saved your Nuggets and Big Nuggets, now is the time to sell them, as he will pay you a huge amount of money for each one. He pays a fair bit for other items to, so if there are some that you don't need and want a bit of extra cash, feel free to sell them.
Also talk to the Battle Girl south-west of the Nurse's counter. She'll give you a Black Belt ! Cool. Now head back outside. First, let's head east back over the white bridge and further east over the yellow one. When you move toward the item, the three Shadow Triad Members will appear.
Not these guys again! They'll almost immediately challenge you to fight. If you choose 'Yes', you'll be battling all three in succession. Between each battle, you can opt to quit, but doing so will cause all three will leave. Either way, you can rebattle the trio once per season.
If you choose 'No' before battling the first Triad member, you can prepare your Pokemon properly, before taking them on. They're quite powerful, so be careful! The second battle is a Triple Battle and the third a Rotation Battle, so you may want to reorder your party prior to beginning.
Trainer Battle: Shadow Triad Member
Triple Battle: Shadow Triad Member
Rotation Battle: Shadow Triad Member
Once the last of them has teleported away, head over and grab the PP Up that was behind them. Now head back west, to the Pokemon Center. Heal your Pokemon, then head west, then north. Continue north past the building to your right until you see an intersection.
Take the path leading west. In the building to your north is the former Icirrus City Gym . If you can make it through all the puzzles to the very top you can speak with Brycen, the former Gym Leader. You don't get anything for doing so but Black/White players will appreciate the throwback.
Once you're done, enter the house to the south. If you talk to the man here, he'll ask to be shown Pokemon. Now, he will give you an item for each category of Pokemon that you show him, which all depends on how many Levels it's been trained since it was caught or you gained ownership of it.
If you show him a Pokemon that has gained between 25 and 49 Levels, the man will give you an Exp. Share . If you show him one that has gained between 50 and 98 Levels, he'll give you a Cleanse Tag .
Finally, if you can show him a Pokemon that's gained a whopping 99 Levels (so you'd need to gain ownership at Level 1 and train it all the way up to Level 100), the man will give you a King's Rock . The woman here is also of use, telling you the happiness of any of your Pokemon.
Once you're done, head back outside and backtrack to the intersection. Now head east and enter the house there. As soon as you enter, a woman will come up to you and lead you in. The three of them will go a little crazy and will eventually ask you a question for a quiz.
You can then enter your answer. If you give the correct answer, you'll receive an Antidote . If you get it wrong, you'll receive Parlyz Heal . You can take the quiz once a day, with questions changing between days. Feel free to come back if you really want. Once you're done here, head back outside.
If you head north from the intersection, you'll reach Dragonspiral Tower , where you can take on Reshiram or Zekrom after defeating them in N's Castle. If you haven't yet explored N's Castle , we'd definitely recommend going there first, otherwise there's little point in exploring the tower.
Other than that, there are two last places to explore, but this can only be done during Winter. Feel free to set your DS or 3DS to a Winter month (April, August, December), then re-enter the game, head into a building and back out. When you do, it'll be set to Winter!
Once it's Winter, move down the steps east of the Pokemon Center. Slide over the ice to your south, then head south-west. When you reach some steps moving up to your west, head south from the foot of them. You'll move up a pile of snow. When you do, head east over to the house. Enter it.
Inside you'll find a Roughneck who just happens to be an ex-Team Rocket member, all the way from Kanto. Kind of cool. Talking to the Ace Trainer here will cause something interesting to happen. Once you're done, exit the building and jump down the ledges below. Head back to the Pokemon Center.
Now head up the path to the west of the Pokemon Center leading north. Continue until you find a large pile of snow creating a ramp up to an area above near the entrance to Dragonspiral Tower . Move up this ramp and head north through the Tall Grass. Past it is some NeverMeltIce . Nice!
Backtrack to the Pokemon Center. Guess what? That's everything! Don't forget to set your DS or 3DS back to the proper month and enter and exit a building to have it reset. From here, you can continue your adventure by heading north to Dragonspiral Tower .
Or you can head west from the Parasol Lady south-west of the Pokemon Center into Twist Mountain . Skip ahead to the section you wish to explore, although it's recommended that you explore Dragonspiral Tower.