none
no, these Pokemon are unknown in Pokemon platinum
once you get so far in the game, an event similar to the ones in Pokemon Pearl and Diamond will happen, only with giratina and the Reverse world
Once a a day in Pokemon Platinum
You need the event Oak's Letter for it and once you get it go to Route 224 which is found by going through a hidden entrance by the exit of Victory Road.
you have to get it in an event. it is called the members pass, and once you get it and go in the house a man will put you in a bed. once you sleep you will wake up on newmoon island, where you can catch Darkrai.
No, even with the event.
receive from Haley in,"My Pokemon Ranch" once you meet the requirements. then, transfer to platinum.
no
You have to go into the GTS once
Beat the Pokemon league again and go back to spear pillar and you will see dialga again.
It was a Pokemon event that was held in local Toys r us stores a little while ago where once you inside and connected your DS they sent you a lvl. 50 Shaymin.
lvl him up once in Mt.Cornet