I managed to get the card from the mail man but if I go to the inn it keeps saying the door is tightly shut, I already beated the Sinnoh league and got the national dex, maybe there is another requirement I'm missing? because that is the only event I haven't managed to trigger, all the others like Oak's Letter and Secret room have worked without problem, even the Arceus Flute worked and I got that one with an AR Code, this because here in Mexico those events take longer to arrive
Edit: My bad! it does works, it was my mistake, I needed to do the Sailor's son quest first, you know, to see Cresselia ^^U
The japanese wondercard does work on Platinum USA ^^