How to Make Easy Money in Pokémon Black and White

Selling Your Feathers

Go to Driftveil Drawbridge or Marvelous Bridge. They are located at the west side of Route 5 or the east side of Route 16, respectively. Both routes are adjacent to Nimbasa City. Marvelous Bridge is suggested for easy EXP while collecting feathers, while Driftveil Drawbridge is suggested for lower leveled Pokémon.

Walk around on the drawbridge. Make sure you can hear if there are wing-flaps.

Look around for small shadows, if you hear wing flaps.

Walk over the shadows. You will either get one of seven different kinds of feathers or battle against Ducklett (on Driftveil Drawbridge) or Swanna (on Marvelous Bridge).

Repeat steps 1 through 4. Collect as many feathers as you can.

Go to the nearest Pokémon Center and sell them, when you have enough feathers.

Battling Trainers Daily or Weekly

Enter into Nimbasa City's Big Stadium and Small Court and battle trainers inside. The number of trainers and the levels of their Pokémon increase as progress is made. Big Stadium trainers are often inaccessible during 2 PM~4 or 5 PM, while Small Court trainers are often inaccessible during 10 AM~11 AM or 12 PM.

Defeat the Elite Four.

Defeat Cynthia located in Undella Town. She is located in the first house west of the Pokemon Center. Undella Town is unavailable to be accessed until the defeat of the Elite Four. Upon defeating Cynthia, she awards you with a large sum of ₽15,600, doubled to ₽31,200 if you used a Pokemon that held an Luck Incense or Amulet Coin during the battle.

Enter into Opelucid City's Battle House, located right next to the entrance to Route 10. Battle both Ace Trainers.

Enter into Castelia City's Game freak building and battle Morimoto. Unavailable until the defeat of Ghetsis.

Enter into the seventh floor of Victory Road, easily accessible from the Pokémon League, and battle Cheren. Unavailable until the defeat of Ghetsis.

Enter into Juniper's lab and battle Bianca. Unavailable until the defeat of Alder and only on Saturday and Sunday.

Go to Nimbasa City's Ferris Wheel. Battle a person in front of the entrance.

Take a ferry on Royal Unova in Castelia City. Battle trainers within time limit. Only available in the evening and the number of trainers range from 3 to 7, depending on the day. Defeating all trainers in the ferry within time limit grants a rare delicacy from other regions, which can be sold to the maid on Route 5 or kept as prizes. Unavailable until the defeat of Ghetsis.

Selling a Casteliacone

Go to Castelia City. [Note: This only works on Tuesdays, and not in winter]

Walk up Mode street, which is the second from the right.

Talk to the last person in the line for ice cream stand. Buy a Casteliacone for ₽100.

Go to Nimbasa City and exit through the upper-right exit toward Driftveil Drawbridge.

Enter the parked caravan/trailer and talk to the girl inside. She will buy your Casteliacone for ₽2000.