catch them in pal park. to check which region they are in use <www.serebii.net>
It depends if you migrated it or not
You have to migrate them, or trade with a person who migrated it.
no sorry
It's not possible. After a Pokemon is migrated to diamon pearl or platinum, it can't be brought back
I'd say mewtwo
buy the Pokemon platinum book
Yes. it does allow you to catch a lv.1 regigigas
The 151st Pokemon is Mew and is unobtainable in Pokemon Platinum.
no you can't find a torchic egg in Pokemon platinum
you have to go to the pal park and enter the catching show it's in route 221
you cant get them unless you migrated or you usec the toys r us event
no. just go to the pal park and then go around the places which are similar to the type of the migrated Pokemon