How do you make money?

Should I reveal my secret? Hmm...
sure! Why not.

I run around with a mask over my face, a Pokéball at hand. i burst into the nearest bank and demand them to fork over the cash.

 

I just battle other trainers. You get some levels and some money. It works out so well!

 

Nimbasa Stadium battles, the Striaton daily double-battle, and Black Tower. I repeat it every day as I am training some mono type teams at the moment. I also get a colorfed flute daily from the guy not far from Undella Town, and sell that to the maniac in Undella. It's at leasy $7500 a pop there.

 

Battle the "Rich" Titled Trainers.

 

I usually just battle the trainers at the Nimbasa Stadiums, but...

I take a Lvl 100 Persian with Pay Day and an amulet coin, so every time I use Pay Day I earn an extra 1000 pokedollars which is pretty useful!

Pay Day multiplies Persian's level by 5, the result is the amount of bonus money you earn. In this case 100 * 5 = 500.
The Amulet Coin doubles the amount of money you earn, which also doubles the pay day bonus... easy 1000.
Example: If I fight a Trainer with 6 Pokémon... BOOM!! 6000 pokedollars, plus the normal earnings from the battle!

 

So for the first time ever I ran out of money, and figured this way of making it:
You need a weak Pokémon with the ability compound eyes, and a Pokémon over level 60 with the ability frisk, that can learn Thief. So basically, Stantler, Banette, or Gothitelle.

What you want to do is have the Pokémon with compound eyes be the first in the team, but have it be fainted. Outside of battle, compound eyes increases the rate at which wild Pokémon have held items.
Of course, your Stantler, Banette or Gothitelle should be second, so that they get sent out instead of your compound eyes Pokémon. If the wild Pokémon is holding an item, you'll frisk it, and you can thieve it. Remember to take it from your Pokémon once the battle ends, otherwise you won't be able to thieve anymore.

With this set-up, you can farm any item held by wild Pokémon in the game.

Where I go to use this, is Giant Chasm. In the crater forest area, you can usually run into Clefairy, Solrock, and Lunatone. They all have a 1% chance (5% with Compound Eyes) of holding Comet Shards, which can be sold in Icirrus City for 60.000 to the ore maniac. They also have a 5% (20%) chance of holding a sun or moon rock, even clefairy, which can be sold to the same guy for 3000. If your Pokémon doesn't frisk anything, or it frisks a Leppa Berry from Clefairy, just flee (You can thieve a leppa berry to restore Thieve's PP)

I recommend using the Dark grass, and maybe even a second Pokémon with Thief (Even if they don't have frisk) so if you get a double encounter you've got extra chances of getting a held item. If both Pokémon are holding an item, frisk will only work on one though, so you might want to take your chances with the other one - You can only lose time.
I also recommend turning off battle animations for quicker looting. Enjoy!

 

I usually just go into Nimbasa City and battle the trainers in the stadiums while I have the Amulet Coin on the first Pokémon in my party.

 

Its called stealing