With enough diligent practice, you can create a two-person telepathy act in which you may introduce your friend as a medium, as you play the part of his assistant. Your friend sits in a chair, blindfolded beyond every suspicion, and you go into the audience. Members of the audience offer personal items, and you transmit the thoughts of these items to the medium, who successfully names every one.
If you want an idea of a powerful act of this nature, look into the act of The Evasons or that of The Piddingtons. Both demonstrate extremely successful two-person acts, the former being modern, the latter being a few generations old; this goes to show that old ideas are the best new ideas.
Above all, I'd like to advise that you consider that no effect is set in stone. A new presentation is always available, and this goes for presentations with more than one performer as well. Penn and Teller do the Cups and Balls with two people, as well as Houdini's Needles. Both are hard to imagine as successful two-person illusions, but each was simply re-staged to accommodate an additional operator.
When adapting a routine for two magicians, staging is more important than how inherently adaptable the routine is. Never take it upon yourself to impose limitations. Rather, let any limitations arise naturally.