It's a shame. But then, being multiplayer was never PMD's strongsuit. In fact, the previous games only made it so you could rescue other players via wifi/wireless connection, not explore. It wasn't really practical doing that either, since you had to know another player in real life/online, give them a password, and then wait for them to rescue you. A lot of the time (if I lost) I would just turn off my DS and start the mission over from where I last saved.