If you have the English version you can press the R Button, the X Button, and Left on the D-Pad and enter the password P8M2-9D6F-43H7
the japanise version you rather had to be at the premier of the Pokemon 9 movie or have an action replay
to get Manaphy without cheating, you have to have Pokemon Ranger, beat a certain mission, and then somehow transfer the Manaphy egg to Diamond or Pearl.
speacial manaphy mission on Pokemon ranger 1 or 2
You can do that mission in both ranger games. Pokemon Ranger and Pokemon ranger shadows of almia.
There isn't one
there are no more missions
Manaphy is not originally in Pokemon Diamond. In order to obtain it (without an action replay) you must play all the way through the game Pokemon Ranger. In the last (extra) mission of the game you can acquire the manaphy egg and then send it over to Pokemon diamond.
It's not, it's on Pokemon Ranger, once the mission is complete, you can transfer a Manaphy Egg to Pearl or Diamond
you cant... but if you have the original Pokemon ranger you can finish the game get the hidden ranger net mission, you have to finish that mission and then you get the manaphy egg, you later transfer it to your game and there you go.
There is no trainer in Pokemon Platinum with a Manaphy. However, you can trade with someone who has a Manaphy, or complete the special Ranger mission in Pokemon Ranger and transfer the Manaphy egg over to Pokemon Diamond, Pearl, or Platinum.
Right now, It's only available through a distribution from Pokemon Ranger. If you can get a used Pokemon Ranger Shadows of Almia game, on it you could possibly gotten a Manaphy Egg mission. You need a special code, which is revealed on Pokemon.com, to unlock the mission from the ranger net in Pokemon Ranger.
The only way to get manaphy on Pokemon diamond is to either trade it. or buy Pokemon ranger and beat the manaphy mission then manaphy will be obtain able
you get the manaphy mission after you obtain ranger net the way to get the mission is to press R,X and left then enter Mg35-Cpb8-4FW8 then you'll get the mission ;3