How do you activate complete pokedex 100 complete on Pokemon platinum?

You must see (Not catch) all 210 pokemon. Manaphy can be seen by looking at the book in the mansion south of hearthrome.

I'm not sure what you mean by the question. If you mean "How do you complete the Pokedex in Pokemon Platinum", then that's simply by finding the Pokemon. You don't have to catch the Pokemon. All you...

see all the Pokemon on the pokedex well,all i know is that there is 210 Pokemon in sinnoh,and around 400 in the game.Some of them are event Pokemon,for E.G. shaymin,Arceus,regigigas might be event...

You have too trade from diamond and pearl because not all the Pokemon are in platinum and you need events or an Action replay. Hope that helps.

you have to beat the Pokemon champion and later on in the game you will complete it