You don't
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.
Your cant get it without Event
get An Egg From Ranger And Transfer It To Pearl
you cant catch it, you have to trade it from Pokemon ranger
he comes from Pokemon ranger. there is a misson for the manaphy egg. after the misson you connect it to Pokemon pearl.
There is no way to send regice regirock and registeel from ranger to pearl. the only Pokemon that can be transferred from ranger to pearl is the manaphy egg.
there is no event for manaphy you have to get it from Pokemon ranger
you need Pokemon ranger to get manaphy
Manaphies are unobtainable in Ruby as it is a Generation IV Pokemon.
You get it from Pokemon Ranger, from Fiore or Almia, in the form of an egg.
Manaphy and Darkrai.
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.