Exotic missions are always designed to be played solo. Everyone can complete all the exotic missions on normal playing solo (except maybe zero hour due to the timer) and none of them has a mechanic that involves more than one person (aside from maybe the easter egg at the end of zero hour which I don't remember if it was for the catalyst or the ship). The only activities that have mechanics designed around more than one person are raids and dungeons like in the nightmare of gahlran where you have to pick up two different symbols and go to the nightmare realm in two different paths to be able to start the damage phase