You cannot change his from in Pearl only Platinum.
you can't
no not at all
Veilstone City.
You can't change Giratina's form in Pokemon Pearl (that includes Diamond). You can change Giratina's form in Pokemon Platinum (that includes Heart Gold and Soul Silver). You can change Giratina's form with the Griseous Orb. To change Giratina's form give Griseous Orb to Giratina and then take it off and Giratina changed its form.
No, it never evolves, but you can change it's form on Pokemon diamond/pearl.
You can't get origan form in Pokemon pearl. Sorry...
You can't change Shaymin into Sky Form in Pokemon Diamond (that includes pearl). You can only change Shaymin into Sky Form in Pokemon Platinum (that includes Heart Gold and Soul Silver). You can get the Gracidea to change Shaymin into Sky Form.
You change his form in pokemon diamond pearl and platnium, you need a special key though for something in eterna city
In Veilstone City. The south-east of Veilstone city.
They power up certain moves and change Arceus's type/form!
shaymin needs to have a gracedia flower to change into sky forme but it will return to land form when it is dark or if it comes into contact with ice, im not sure if it can change formes on Pokemon pearl though
If you bring a deoxys to any of them it will change its form in favor of its attack, defense, speed, or normal.