Sandstorms a' Brewin'!
All of the battles fought in the desert of Route 4 and the Desert Resort will have a constant Sandstorm weather effect, which inflicts 1/16 a Pokemon's max HP in damage each turn. Equip the Leftovers you hopefully picked up in the Castelia Sewers or use Rock-, Ground-, or Steel-type Pokemon, who are unaffected by the sandstorm's damaging effects.
|Sandile||/||Lv. 14 ~ 17||35%|
|Darumaka||Lv. 14 ~ 17||35%|
|Trubbish||Lv. 14, 15, 17|
|Minccino||Lv. 14, 15, 17|
Route 4 (White 2)
You can actually visit Route 4 before getting your Insect Badge, but you just can't go very far in it until afterwards. Regardless, head north and fight the Backpacker there with his Sandile L16 and Herdier L16. Head west of the Backpacker and then fight the PKMN Breeder, who has a Drilbur L16 and a Marill L16 — watch out for her, because she, like every other PKMN Breeder in the game, will fight you again every time you leave the area and return!
Now head north and talk to Colress, who will use some sort of a thing to move all of the Crustle blocking the path. Afterwards, he'll challenge you to a fight!
After beating him, he'll give you a Protein for your trouble to help raise the Attack stat of your Pokemon, then he'll walk off. Well, at least he cleared the path for you.
Before you head that way, check out the bottom left corner, heading down the steps and fighting the two Fisherman there if you'd like. The top one has a Basculin L17 and the bottom one has a Psyduck L16 and a Basculin L16. Right by them is the Mystic Water, a held item that boosts the bearer's Water-type attacks' damage by 20%.
Anyway, head back up the stairs and to around where Colress was, then head north, down into a little village thing in the dunes. The house to the west can actually be entered. You can talk to the lady in there and she'll play a game with you, where she'll make the cry of a Pokemon, and then you need to guess which Pokemon it was; if you answer correctly, you'll get a Poke Toy which can be used to run from a wild Pokemon fight (though it uses up the item). Presumably you can do this once per day. Directly outside of this house is a hidden Red Shard, which can be found with your Dowsing MCHN.
Right by the building, back on the main path, are some Twins you'll have to fight in a Double Battle. They use a Cottonee L20 and a Petilil L20. Just north of them is a Rich Boy with a Herdier L22 on his team. Equipping the Amulet Coin you picked up in Castelia City is a good idea to earn some extra money. If you use the Dowsing MCHN just above him, you can find a hidden Hyper Potion.
To the west of the Rich Boy and then north, behind the house, is the valuable TM28 (Dig). This TM is very important due to its Ground-type and respectable 80 power, so go ahead and see if any of your Pokemon can learn it, because it's quite useful to have around.
Just to the east of the Rich Boy is a Lady — again someone you want to have the Amulet Coin equipped for. She uses a Liepard L22. Directly south of her is a Stardust, which can be sold for some money, and the house directly to the right of her has two Ace Trainers in it; the boy will want to see a Pokemon that has an Attack stat above a certain number. If you have a Pokemon with a stat above that number, he'll give you a Swift Wing; if you have one with exactly that stat, he'll give you a total of five Swift Wings instead. You can do this once a day. The number will change, too.
The house directly to the east has a boy who will trade a Cottonee for your Petilil (this is in White 2 only, obviously). That's a great way to get a Cottonee in White 2, since you can't get it in any other way. Right next to him is the BrightPowder, which is a held item that lowers the foe's accuracy by a little bit in battle. It can be handy to equip. Just outside of that house is a Backpacker who will fight you with her Woobat L21 and Pidove L21.
Keep going east, past the Backpacker, and you'll find a clearing. There's some hidden Stardust in the sand and there's a Pokefan ♀ with a Darumaka L22 on her team. It can hit surprisingly hard, so be careful! There's a Green Shard hiding nearby, plus you can walk behind the buildings to the northeast of her to find a Light Clay, which, when held, increases the duration of the Pokemon's Light Screen and Reflect attacks, which is very nice if you plan on using those.
Feeling Braviary on Mondays!
If you look around the houses back here by where the Pokefan ♀ is on Monday, you can find a Braviary L25 sitting outside, ready for you to battle it and hopefully catch it. Braviary makes for an amazing Flying-type Pokemon for your team, with high Attack, Speed, and HP, and since you can't catch Rufflet for a long time (and also since Rufflet normally evolves at level 54), this is a great catch. Not only that, but this Braviary even has its Hidden Ability, Defiant, which raises its Attack by two stages if any of its stats are lowered. Keep in mind that this is for White 2 only; Black 2 players get a Mandibuzz instead, so read in that section if that's what you're playing.
Go back to where the Backpacker was except now head south and you'll find a Pokefan ♂. He uses a Growlithe L21 and a Sandshrew L21. The house next to him has a few people in there, although the Black Belt inside will give you a generous 3 Sitrus Berries for talking with him. Finally, hiding right behind the house is a Yellow Shard (again, use the Dowsing MCHN).
Now you should be done with everything in the village area down here, so go back to the center part (over to the west, just above where you fought Colress) and then head north, climbing up the stairs until you see a Backpacker to your right and then a girl to your left. Over by the girl leads to the Desert Resort, which you can go to now, if you want (it's optional, but nice), or you can just go on and fight the Backpacker with his Riolu L21 and Timburr L21, take him out and then head north to reach the Join Avenue, which is on your way to Nimbasa City!