Dream World Rain-teams tend to head in two possible directions: either Offensive or Stall. While both have their own positive and negative effects, it is safe to say, Rain has become the most dominant weather in the tier.
After the Blaziken ban, Rain offense became even more super-effective thanks to it's amazing coverage and a versatile of nerve-wracking sweepers. Offensive rain-oriented teams are most commonly consisted of: Keldeo which is an absolute monster and no joke under the favorable weather, it has the ability to OHKO many bulky-pokemon with its STAB Hydro Pump and Secret Sword, it also appreciates occasional Tail Wind support during late-game from Tornados while in pinch; Volt-Absorb Raikou is an other fantastic addition to the Dream World meta game, it's blazing speed and access to a multitude of powerful attacks give it the full-potential under rain and is a decent Thundurus, Tornados and Keldeo back-up check; Toxicroak has proven to be one of the most underrated rain-sweepers in fifth gen, permanent rain and its ability Dry Skin increase its survivability, it also packs numerous resistances and removes Toxic Spikes from the field which is really beneficial; Almighty Thundurus on the other hand is an excellent top-notch sweeper, with access to Nasty Plot and Prankster it's presence becomes even more deadly as 120 BP STAB Thunder decimates anything that does not resist it, priority Thunder Wave is a great option which cripples many sweepers and keeps the offensive momentum up; Tornados abuses rain in a similar fashion by spamming continuous STAB Hurricanes which eventually become pretty difficult to deal with; Jirachi is not that often seen on an offensive team considering how common Chandelure is in DW but rain halves it's fire-type weakness which essentially give it many opportunities to be golden. To make an efficient use of rain-offense, entry-hazards are much appreciated and Deoxys-S is a solid candidate for this job. If your team has no reliable way of dealing with other weather inducers Dugtrio is the perfect man for the job.
Stall is somewhat of an operational play-style if used wisely and appropriately. Tentacruel is the back-bone of every stall-team and is something you must consider, Rain Dish plus its access to Toxic Spikes annoy many well-built teams and is something that couldn't be neglected; Skarmory is an ideal choice which deals with Dragons such as Haxorus, Dragonite and Salamence, it also stacks spikes which slowly wears down opposing mons by phazing under a preferable weather; Amoongus utilizes it's numerous resistances and amazing ability Regenerator to wall the most common threats to rain-stall such as Calm Mind Keldeo and Swords Dance Breloom, it also has the access to spore which makes it an amazing utility wall; Chansey is your special wall and makes an effective use of its natural bulk paired with Eviolite; for the last slot you've gotten several choices, Gastrodon absorbs water-type moves and provides an electric-type move immunity; Jellicent acts as a spin-blocker which benefits stall in a long run. Rain-stall gets a very difficult time against many variants of Manaphy who heal of their status and regain HP back with Hydration and literally demolishes stall after a boost.
As Omicron already said
this and
this are great resources to refer to if you're wondering about the common sets. I'm not too familiar about sun in Dream World, however Omicron has brought-out many excellent points.
As of Genesect, I absolutely love the Focus Sash + 4 attacks set which picks off so many battlers. I normally run U-turn / Ice Beam / ThunderBolt / Flamethrower with a Naive Nature and has worked out wonders, impressively boosting me to 1709 with a rapid-spin support. On the other hand, Rock Polish set doesn't sounds like a bad idea either which essentially confuses your opponent to make a bad decision and acts as a perfect late-game cleaner.
Modest is definitely the way to go on Chandelure, Timid nature doesn't accomplishes much in DW. More power is always appreciated while revenge killing. Timid allows you to reach 426 where Modest boosts your speed to 388, and allows it to outspeed respectable portion of the unboosted metagame. The main idea between Modest is to get an instant OHKO on many threats which are otherwise impossible with Timid. Taylor's
Sand Enduring Territory was a prime example of Sand HO in the Dream World tier. Since Blaziken is now banned from the tier, SD Breloom or Calm Mind Keldeo would make perfect replacements for its spot.