I am pleased to annouce that thanks to DP Master finding some nice tools on a Japanese Wiki, I have successfully learned how to change Wild Pokemon! The following is a tutorial on how to do it.
Discussion with link to Poke Info Editors.
http://z3.invisionfree.com/diamondpearlhac...hp?showtopic=16*The program is in Japanese (must know Japanese Pokemon names)**This program only works with the Japanese Versions (Haven't tested English)**ROM MUST GO IN SAME FOLDER AS APPLICATION OR YOU CANNOT SAVE IT!*First: open Up the program called, "Habitat"
Second: Go up to the upper left-hand corner and click the area circled in red in the image below.

Select the FIRST option.
This will bring up a window asking to load your rom, do that.
Third: Go to the left where there is a large scroll list and scroll down until you find, the numbers 201. This is the first route you will encounter.

Fourth: Up at the top will be many little scroll boxes, With either 2 or 3 beside them. These are the pokemon that appear normally on the routes and their levels. Change these to whatever you want, In my example I used Charmander.

Fifth: Go down to the lower right-hand corner and select the button there. THIS IS VERY IMPORTANT, IT WILL NOT WORK OTHERWISE.

Sixth: Go up the same area in step 2 where you opened your rom, but this time select the SECOND option.
The saving time takes a while, depending on your computers speed, have patience. If your rom is not in the folder with the application, it will never finish saving.
Open your rom with your favorite emulator and... TADA! Charmanders on route 201!