Follow these steps carefully. Complete the story mode by stopping Gordor, the Go-Rock Squad's boss, at the Fiore Temple by successfully capturing Raikou, Suicune, and Entei. The credits will roll, and the game will be saved. Go to the Pokemon Ranger menu and you will see the Ranger Net has been added to the list of choices. Press it and you will enter Ranger Net. You will see the option "Play a Special Mission". Press it and you will see the "Befriend Deoxys?!" mission. Complete it, and then return to Ranger Net and you will see the "Rescue Celebi!" mission. Clear that one, and then return to Ranger Net for a third time. Click on the "Mew, the Mirage" mission and clear it. Then go back to Ranger Net and press the R button, X button, and Left on the Control Pad all at the same time to bring up the "Enter the Password" feature.
Press it and enter this password for the American version: P8M2-9D6F-43H7. Once you do that, the "Recover the Precious Egg" mission will be added to the "Play a Special Mission" option. Clear it, and you will recieve the Manaphy Egg.
Answer To obtain a Manaphy egg in Pokemon Ranger, you must complete the special mission related to it. The mission simply requires you to chase and corner members of the Go-Rock Squad and retrieve the egg. However, this is not a normal mission in the game.
In Japanese versions of Pokemon Ranger, you must attend a Nintendo event and download the special mission. In American and australian versions, you must enter a password in the password screen to unlock it.
In the Ranger Net feature, hold down R, X and the left directional button to unlock the password feature. In there, type P8M2-9D6F-43H7. You should note that that particular code does not seem to work for the UK versions.
you have to go to the Ranger Net and play the special manaphy mission.
For the UK version you should try out the code Mg35 - Cpb8 - 4FW8
After this, transfer your egg over to your pokemon pearl or diamond, hatch it, and then put your Manaphy into the day-care, wait for and egg from that, and then you will have two special pokemon.