Member card on pokemon diamond?

how do I get the member card on pokemon diamond to get in to the harber inn

Hi,

You need the Mystery Gift. Here is information I found on another website:

You really cant without a Nintento event... unless you use Mystery Gift. If you go to Jubilife TV Station, there is a man on one of the floors (just talk to everyone, you'll find him) that will ask you what you think of TV. Answer, 'EVERYONE HAPPY.' Then, he will ask for feedback, and answer, 'WI-FI CONNECTION.' Then save the game, restart it, and Mystery Gift will be one of the options. If you have gotten the National Pokedex, or at least beaten the Elite Four, you can select 'obtain gift via WFC.' Your gift will be downloaded off WI-FI connection, and you can get the membership card this way. I cant guarantee you will get that exact item, but you might. Good luck!