Almost as soon as you enter the Dreamyard, a Latios (Black 2) or Latias (White 2) will show up and growl at you. It'll run off shortly afterward. Want a Latios/Latias? Well, you're going to need to chase it down in the Dreamyard in order to have a shot at catching it, but make sure you've got plenty of Ultra, Dusk, and Timer Balls to improve your odds of catching it when in the battle.
Start by ignoring the bush that requires Cut and just keep heading east, slipping through the gate. You'll see the Pokemon fly off to the west. Now go back and Cut the bush down, then head into the middle area of the ruins. Latios/Latias will fly off again, although this time over to the east.
Head over to the stairs to the east and climb them. Up there, Latias/Latios will fly by once more, this time to the west. Head west yourself, all the way over until you can move south. Down there, just shy of the item, you'll run into Latios/Latias once again. Pick up the Ultra Ball, since it's right there, then head all the way back to where the stairs were and keep following the path east until there's nowhere else to walk. After saving your game, step on the space at the very edge of the ruins and Latios/Latias will appear once again, although this time it will fight you!
They're both Dragon/Psychic-type Pokemon, giving them a variety of resistances. Latias tends to have more resilience, while Latios has slightly higher offensive stats. They're both pretty tough to catch, though. Timer Balls are your best bet after 10 turns have elapsed. A Dark-type Pokemon works excellently against them, because their only attacking move is Psychic. They can also heal you with Heal Pulse, only making your skirmish against them easier. If only they'll stay in the Poke Ball you toss at them, you'll be in business.
After catching the Eon Pokemon of your version, be sure to pick up the Soul Dew that appears behind you. It powers up Latias and Latios' Special Attack and Special Defense by 50%, making them incredible Pokemon to use in combination with their strong moves.
Anyway, there are a few more items scattered around the Dreamyard. There's TM85 (Dream Eater) sitting by the window directly south of the stairs, which you should pick up on your way back down if you haven't already. There's also a Rare Candy over to the west in the grass over there.
There's plenty more, too. Return to the fence you slid through early on, in the eastern part of the Dreamyard, and pick up the Moon Stone sitting underneath the ledge where you fought Latios/Latias. Now that you've gotten Latios/Latias out of the way and hopefully caught, make your way down the stairs you see over there to enter the Dreamyard's basement.
The basement isn't quite as crowded as it was in the original Black and White, but there are still a few Trainers for you to fight down there. The first you'll run into is a Psychic, and he's got a Hypno L62 and a Dusclops L62. Over to the east of him is an HP Up, along with a Researcher who uses a Gastly L63 and a Skuntank L63.
To the south and then over to the west is a Scientist, who uses a Klang L63 and a Porygon L63. Pick up the Dawn Stone right by him, and then head over east, where you'll find a Psychic with a Chingling L62 and a Mr. Mime L62.
Just past her, you'll wind up at some stairs that lead you back up to the main part of the Dreamyard, except in a previously inaccessible area.
To the northwest, you'll find a School Kid. He's got a Shroomish L63 and a Tangrowth L63. Right past him, hiding just outside of the furnace, is a PP Up.
Back at the stairs, head south and then west to find some thick grass.
|Watchog||Lv. 64, 67||25%|
|Liepard||Lv. 64, 67||25%|
|Munna||Lv. 65 ~ 66||20%|
|Golbat||/||Lv. 65 ~ 66||10%|
There's also a Youngster nearby who uses a Slakoth L63 and a Slaking L63. Take him out, then keep going west until you see some more ruins. Don't go in them just yet; instead, keep going west into the forest so you can pick up the item, although watch out, because there's a School Kid who will ambush you! She uses an Igglybuff L63 and a Lickilicky L63.
After beating her, pick up the Reaper Cloth nearby, which can be given as a held item to a Dusclops and then traded to evolve it into Dusknoir.
Now just head north, over by the stairs leading down, and use Strength to push a boulder into the pit to create a shortcut, should you want to come back this route. Got that? Good, now head down the stairs back to the basement to finish up the Dreamyard.
|Raticate||Lv. 64, 67||25%|
|Golbat||/||Lv. 64, 67||25%|
|Munna||Lv. 65 ~ 66||20%|
|Liepard||Lv. 65 ~ 66||10%|
Pick up the Iron found in the thick grass directly to the north and then the Psychic Gem sitting in the middle of the patch of grass to the northeast.