Do you have to be inside toy'r'us to get Darkrai?
I think as long as you have a connection to toys 'r' us, you're good to go.
If you get a member card i think you can get Darkrai. Unfortunately you can only get it at a Pokemon event. But if you want a Darkrai, and have the 'walk through wall' cheat, you can get Darkrai! Have the national pokedex, go to canlave city. Talk to the sailor and sail to Fullmoon/Newmoon island. Once you get there, keep walking right until you get to another island. Go into the entrance wich takes…
The Membership Pass grants access to Darkrai. After you get the pass, go to Canalave City and head up. You should see this inn. Before, if you didn't have the pass, you wouldn't be allowed to go inside but with it, you can. Inside the inn should be a bed. Sleep on it and your character will wake up on New Moon Island. Follow the path and you will be led to Darkrai.
You need an event item to get in there. You sleep in a bed and have a nightmare, then find yourself on Full Moon island. It's the event that leads you to capturing Darkrai. There is a person there and you fall asleep,in your dream you are on an island and there is a Darkrai, catch him if you can he is amazing for a level 40.
If you get the member pass coded for Pokemon platnium does that mean Darkrai himself is coded or just the item?
You just get the item. You then must go to the inn in Canalave City, and the man inside will tell you to go to sleep. you then wake up on Newmoon Island, and can catch Darkrai. Afterwards, some words will appear, and then you wake up and find it was all a dream. Darkrai will be waiting in your party or in your PC box for you.