I am currently being taught how to hack pokemon games, starting with diamond.
Here is a max money code I made for an example:
94000130 fcff0000
b21c4d28 0000000
0583d644 000f423f
d2000000 0000000
All I did was use Cheat Engine and Searched my money in pokemon (from start 3000) and changed my money by buying something, searched for my changed amount of money, then edit the value to 999999 (Max money).
Just a little something I was impressed I could do.