If you actually want the Pokemon, you can either trade for it, or do a transfer thing from Pokemon Ranger (I think).
Alternatively, you could cheat with action replay.
If you just want to spot the Pokemon and add it to your national pokedex, go to the owner of the Trophy Garden south of Hearthome, go into the room where he is, and read the book on the table. Then, manaphy will show up and be added to the pokedex.
no you can't find a torchic egg in Pokemon platinum
You cannot find zekrom in pokemon platinum
You can't find rayquaza in pokemon platinum.
The underground
migrate it
Ash is not in platinum..
You cannot find Lugia in Pokémon Platinum.
You can't find Vibrava on Pokémon Platinum
You cannot find Lugia in Pokémon Platinum.
You can find exeggcute in the Great Marsh in Pastoria City
To find a shiny stone in platinum you have to dig in the underground tunnel.
no you can't find a torchic egg in Pokemon platinum
No, you cannot find a Charizard in Pokémon Platinum, in order to get a Charizard in Platinum, you would have to trade for it or migrate it from a Gameboy Advanced game.
It's impossible to find Mewtwo in Platinum.
how do you find a male houndour in pokemon platinum
Gamestop(:(:(:(:(:(:(:(:
you can find them whilst surfing in route 225 on pearl, i don't think you can get them on platinum.