Mainly the Pokemon from Diamond except Palkia instead of Dialga. If you don't have Diamond, in pearl you can get Cresselia, Darkrai (mystery gift) Shaymin (mystery gift) Palkia Arceus ( mystery gift) Manaphy (special event) and other ones I don't remember
It allows you to get legendary Pokemon and items to get legendary Pokemon. I have a manaphy because of mystery gift. there will be a darkrai and areceus mystery gift at toys r us and at game stop. i missed the deoxys mystery gift. it was on June 29th. I hope that helped!