Instructions
Finish the Power Rangers game's main story line by stopping Gordor, the Go-Rock Squad boss.
Go to the main menu. The "Ranger Net" option should now appear on the menu.
Select the "Ranger Net" Option, then select "Play a Special Mission." You will see only one mission, "Befriend Deoxys?!"
Select and complete the "Befriend Deoxys?!" mission and return to the "Play a Special Mission" screen. You now must complete two more special missions, "Rescue Celebi!" and "Mew, the Mirage."
Go to the Ranger Net screen. Press the "R" button, the "X" button and "Left" on the control pad at the same time. An item called "Enter the Password:" will be added to your Ranger Net menu.
Select the "Enter the Password:" option, then at the prompt enter "P8M2-9D6F-43H7" (without the quotation marks). The "Recover the Precious Egg" mission will now be available on the "Play a Special MIssion" menu.
Complete the mission and you will get the Manaphy Egg. You must transfer the egg to Pokemon "Diamond," "Pearl," "Platinum," HeartGold" or SoulSilver" before it will hatch.