I don't think Platinum would be the American name, as Opal is much more fitting. Palkia is a Dragon/Water type, and he belongs to the game Pearl. Pearls are generally found in the ocean, hence the Water type. Dialga is a Dragon/Steel type, and belongs to the game Diamond. Diamonds are the hardest natural material, hence the Steel type. Giratina is a Dragon/Ghost type, and might belomng to the game Opal. Opal is the gemstone of the month October, and we all know October for its special day called Halloween, which involves ghosts or spirits. The gem is also sometimes associated with bad luck, which is fitting for a Ghost type.
Regardless, I do think there will be a third installment. Can't wait for it. =)
Regardless, I do think there will be a third installment. Can't wait for it. =)