I think it has to be all three shows, but some characters would have to be pushed to background.
Obviously, Grissom, Horatio, and Mac would get the most screen time. But who else?
(this is completely subjective. Feel to agree or disagree).
Tier 0: Grissom, Horatio, Mac
Tier 1: Catherine, Eric, Stella
Tier 2: Warrick, Nick, Calleigh
Tier 3: Danny, Greg, Ryan, Hawkes
Tier 4: Sara, Lindsay, Natalia
Tier 5: Sofia, Frank, Brass, Flack
Tier 6: Robbins, Alexx, Hammerback
I'm assuming (and I'm purely assuming) that, if there's a triple cross-over movie, the top three is set.
However, after Tier 1 and definitely after 2, things are a bit shaky for me (and perhaps for the rest of you as well).
However, my bigger point is, essentially, two first two tiers (whoever they really are) will suck up most of the time. Grissom, Horatio, and Mac are given.
A triple-crossover could mean that they would focus mostly on them, with dashes of the rest here and there. I agree; they would suck most of time.
However, some have implied, though not explicitly stated, that those three having the most time with all others pushed aside would be bad. I disagree on that. I would love to see all three leads interacting, and if they are the only main focuses, that's fine with me - as long as they do it well, I'm fine with it. In fact, if there is a triple-crossover movie, they should ONLY focus on those three. If it's NOT a triple-crossover movie, that's another story, but it it is, the leads need to not only take most of time, but all of it.