How to Make Lots of Money in Pokemon Diamond and Pearl

Talking to the Owner of the Trophy Garden

Go to the Trophy Garden south of Hearthome City.

DO NOT GO INTO GARDEN. Go to the door that leads to the owner, save before you talk to him!

Go into the room, talk to owner. Every time he asks you something say "Yes". He will say he saw a Pokémon in the garden, if it is Meowth, continue, If it is not, restart and try again.

Go into garden in the back and use a Max Repel, keep using the Pokeradar as much as possible, when grass has little sparks, go there, if it is Meowth catch it, if not try again.

Once you have Meowth raise it to level thirty but DO NOT LET IT EVOLVE! It will learn Pay Day; a move which if used, will give you extra money after a battle.

Give it an Amulet Coin and use it in battles.

Beating the Elite Four

Beat the Elite Four before doing this.

Go to Spring Path and then to Turnback Cave. When going to the Turnback Cave, bring a Pokémon that knows Defog and Rock Smash.

Keep wandering until you reach Giratina's room. If you already fought Giratina there will be a free item every time you get there, collect it and sell it.

Using the Super Rod

Way number three requires the Super Rod.

Use it at Valley Windworks, if you get a Shelder catch and see if it is holding a Pearl, if it is, sell it and if you want, release the Shelder.

High Level Pokémon

Ensure that your Pokémon is at a rather high level. This needs to be level 40+.

Ensure that your lead Pokémon has either luck incense or an Amulet Coin as an item they're holding. The player must also have a vs. seeker.

Go down from Veilstone City or left from Pastoria City. Either way will lead you to the same place.

Along the hotel resort area, you'll eventually come across a flight of stairs that directly to Sunyshore. Do not go there. When you pass the stairs, go to route 222. This is the first thing you'll come across.

When you get to route 222, look for a big patch of grass and a sign next to it. Travel slightly up from there. You'll see a trainer sitting there alone. He is a rich boy trainer.

Battle the trainer. You will get a lot of money if you win ($4500+). if your lead Pokémon has either a luck incense or Amulet Coin, you'll get double the money, so you'll end up getting around $12000+. If you have already battled him before, use the vs. seeker near him. He will often battle again.