Batman: The Brave and the Bold will feature Wii connectivity with DS.
According to IGN, a person playing the game on DS can assist players on Wii version using Bat-Mite - a mini-version of Batman.
He can apparently drop things from on high, if the screens over on IGN are any indication. Who knows what else you could use him for.
Bat-Mite was mentioned a few months back, but only that you could play the fella, not help out with him.
The game's slated for September 7.