Moor of Icirrus
Right near the entrance to the Moor of Icirrus, over to the left, is a hidden TinyMushroom. There's also an old guy to the north that will tell you a bit about the history of Keldeo, but that's it. If you have Keldeo in your party, he'll tell you a little more about the story.
Push a nearby boulder with Strength and you'll find a little lake area. Fight the PKMN Ranger nearby, who uses an Accelgor L62, a Kecleon L62, and a Swalot L62. She'll give you a Lum Berry after beating her. Head south of her (if you have Surf, you can just cross the water; otherwise, you'll have to take the long way around it) and you'll find TM84 (Poison Jab) sitting there for you to take, which is a fairly strong Physical-based Poison-type attack.
Return back to the old guy, except this time head north and then a little west. Up there, you'll see a Fisherman, but first walk over to the west and pick up a hidden Big Mushroom nestled into the trees. The Fisherman has a Poliwhirl L60, a Politoed L60, and a Whiscash L60. Over to the east of him is a Green Shard.
Head back towards the old guy, except go east instead of west where I told you to earlier (so northeast of the old guy) and keep going northeast until you find a Heart Scale. Pick that up, then head back and east instead of northeast, jumping down a ledge. Down there is another Fisherman, this one using a Corphish L60, a Poliwag L60, and a Stunfisk L60. There's a little patch of flowers southwest of the Fisherman which have a Dawn Stone hiding in them, which can be used to evolve certain Pokemon such as male Kirlia or female Snorunt. There's also a Rare Candy in the trees in the middle of that little island.
South of that island is a PKMN Ranger using an Escavalier L62, a Skuntank L62, and a Carnivine L62. You'll get a Lum Berry from him after winning. Grab the Full Heal near him, then head west to reach the entrance. That's all to see here, so go on and return to Route 8 to make your way to Icirrus City!