What is the fastest way to earn money prior to the Elite 4 in Black/White 2?

Traditionally, the quick way to make money in Pokémon is doing runs of the Elite 4.

In Pokémon Black/White and Black/White 2, what is the fastest way to make money before the Elite 4?

The best way would probably be to re-battle trainers. You can do so at Big Stadium and Small Court in Nimbasa City once a day, or with any Pokémon Breeder, since they'll battle you each time you leave the area and they spot you/you talk to them again, as many times as you wish. Also, equip the Amulet Coin (that you can get in Castelia, according to Bulbapedia).

In Mistralton city you can fight a trainer over and over again, and he will give you around 10000 each time. He does have 5 strong pokemon that are water types, his name is Jaun.