You get a wonder card when you get an event Pokemon. Sadly their are no events for leafgreen riht now because of all of the new Pokemon ds games.
Wonder cards are something you get after a Pokemon event. They tell you the event, day, month and year.
to get Wonder cards in Pokemon platinum, you have to receive an event item or Pokemon. you cannot have more than 3 wonder cards at 1 time.
They are located at the base of google
The two Mystery Gift options can only be used by hooking up to a machine at a Pokemon event. There is no such thing as a Wonder Gift - there is only Wonder News and Wonder Cards.
you need to go to a event which gives either a Pokemon or a item then you get a wonder card
Because there is!
You cannot, for there is no need of one.
you use wonder cards
There are several different events Nintendo holds where they give out free rare Pokemon, items, etc. on Wonder Cards. Check Pokemon websites like Bulbapedia for dates on when these events are held. :)