Part of the amusement of Battle of the Network Stars was Howard Cosell, who wanted to be a serious journalist but also was willing to do almost anything to be on prime time television, giving it his all. He was on all but one of the shows (even in 1988, by which time he had been let go by ABC), and I'm sure he was a draw. I don't know who you'd get today with that kind of a name who would be both enthusiastic and somewhat dismissive at the same time. (Bob Costas, even though he's with NBC?)
Also, do you open it up to other "networks"? ("Tonight - Nat Geo Wild, Discovery en Espanol, and BBC America in an all-star showdown!") At the very least, Fox and The CW probably have to be there.