Scenario two is the only definite one I see them winning.
Scenario 1 contains their next best chance of winning, but even then I think I might give the edge to Zabuza/Kakashi.
The Zabuza/Kakashi matchup pretty much turns in to(if the scenario can be made to fit their best interests) Zabuza delaying Hidan and Kakashi/Kakuzu fighting. Manga intel heavily favors Zabuza/Kakashi because Kakashi has 100% intel on Kakuzu and Hidan, where as they're only knowledgeable about Kakashi based on his reputation and what he showed in their fight vs them, and only know of Zabuza's repuation. Which means in Kakashi's case, raiton clone, raiton enhanced weaponry and raiden, among a couple other things, are completely foreign to the Zombie duo.
Zabuza's bunshin use will come in handy vs Hidan, as it was able to fool even Kakashi, who has arguably the most intelligent bunshin feint feats in the manga. Hidan isn't very bright, and Zabuza could eventually use that as a method of taking Hidan out. That being said, this strategy relies entirely on them turning this in to two 1v1s, and Kakashi being able to prevent any of Kakuzu's masks from assisting Hidan, and with things like raiton enhanced kunai, Kakashi has a chance of doing so, but it'd be interesting.
An interesting ploy by Kakashi could be to set up a raiton clone, have Kakuzu attack it with his threads, paralyze him then strike him with raikiri through his brain(whether this eliminates the hearts or not is beyond me, but even if it doesn't, just dealing with individual masks is a lot easier for Kakashi compared to having to deal with those masks + Kakuzu).