To get all the Techs and 990200 ryo in any version of the game do the following.
Method 1 (from the beginning of the game)
Press A or START until you reach a screen with the two main characters and press SELECT to enter the name change screen. Continue to Step 2.
Method 2 (any time while in-game)
Press START to bring up the menu.
Go to SETUP (last option on the bottom right) and press A.
Press SELECT to enter the name change screen.
Change your character's name to Koganemushi (a japanese beatle).
However, it is currently impossible to display Hiragana in this form, but you can still enter the code.
Enter the following characters:
Fifth column, second row.
First column, second row.
Press B to go back to the last character!
Eleventh column, first row.
Fourth column, fifth row.
Eighth column, second row.
Second column, third row.
Now go to END, which is all the way on the bottom right.
In a fairly well known translation of the game this would be:
square above -
the big white sock
It should be noted that this code does not max out your stats as previously stated.