Need help with a multiplayer feature

I got a Q for the multi player function of Kingdom Hearts 358/2 days.
I got the official card and my little brother has a rom on his flash card.
We wanted to play together but we couldn't find each other. Is it
possible to play together, or does he need the game himself to play with me.

flashcards vary when it comes to multiplayer support for certain games.Whats his?