Lets see.
Tobi>Minato NOW. They were about even before, and now Tobi has the Rinnegan and knowledge on how his techs work. Plus he has his jinchurikis.
Madara>Kakashi I don't really need to explain this.
I think Kakashi would be taken out first by either Tobi or Madara. Either of those two would be able to hold Minato and Kakashi off for a little while (Madara's immense motukon or Tobi's jinks).
Then, it'd be a slightly weakened Tobi and a slightly weakened Madara versus Itachi and Minato.
Madara would take on Itachi, while Tobi would prevent Minato from getting to and hitting Madara..
Madara takes out Itachi with mid difficulty (his Motukon can probably restrict Susanoo, plus his rinnegan techs), but I'm not sure how he'd seal him honestly...
From there on, a weakened Minato would be playing an avoiding game against a weakened Tobi and Madara. But eventually, the Rinnegan techs, Sharingan + EMS techs, and Jinchurikis would take Minato. Tobi and Madara would take advantage of each other's Shinra Tensei intervals. And remember, Madara can summon a meteor while Tobi goes intangible, though Minato can probably avoid it.
I think Tobi and/or Madara would know SOME sealing technique for Itachi.
Eventually, Tobi and Madara would win with high difficulty and a hefty chakra loss.