Hashirama and Naruto.
Hashirama is already the most powerful shinobi in history, and you are pretty much giving him unlimited chakra from Kurama. That would likely make him unbeatable. And you're putting Naruto there to help out. Hashirama can heal without hand signs and has at least three chakra natures (he likely has more). Additionally, one of the abilities is Wood Style, which allows him to make clones, poisonous forests, and dragons. Naruto, on the other hand, is the title character and can pretty much can do everything. He can use multiple Shadow Clones, has two very powerful "modes", can summon multiple toads (the only other characters shown summoning multiple anything at the same are the Animal Path of Pain and Tenten), and is a Jinchuriki.
The real issue in this battle is that full knowledge in the battle is a huge disadvantage for the S/T users. Their abilities rely on deception and surprise, and Naruto and Hashirama knowing how their abilities work is almost unfair. Naruto's techniques really don't have any big surprises. He pretty much attacks head on with a version of the Rasengan, clones, or some other direct attack. From what we know of Hashirama, most of his abilities can't really be stopped, even if you know their coming. Hiruzen knew about Bringer-of-Darkness and couldn't stop it. Kurama knew about the Wood Dragon, and Madara still (easily) landed an attack and drained chakra.
On the other hand, Minato's FTG relies on, first the opponent not knowing that the special kunai are the key to the technique, and second, not knowing that Minato can place the seal on pretty much anything that he touches. In the fight against A and Bee, A was ready to counter Minato's FTG with sheer speed, and now Naruto is faster than A was at the time. Furthermore, if A knew of Minato's prowess in placing seals, he would have at least thought to check Bee's tentacle, and he probably would have been able to counter. Plus, Bee was able to counter, because if Minato had struck Bee, Bee would have killed him, too.
The teleportation aspect of Kamui is useful, but it is not instantaneous and seems to be easily countered. Most of the people that Kakashi has used Kamui on were able to counter it. Deidara avoided getting his head taken off and Obito and Madara avoided the Jubi getting its head take off. Any of the decent shinobi (that were worth anything) were able to counter Obito, as well. Minato countered Obito, Konan countered Obito, Torune countered Obito, and Kakashi, Bee, Guy and Naruto countered Obito.
For Kakashi and Obito, the real advantage to Kamui is its ability to make the user intangible. This makes the person seem impervious to attacks and makes them able to dodge pretty much everything. But the technique relies on the fact that opponents don't really know how it works or what limitations there are. Konan knew about Kamui's limitations, and when she fought Obito, he had to use Izanagi to survive. In a battle, he would only be able to use Izanagi twice, and then he would be blind until he replaced his eyes. Once Kakashi figured out how his intangibility worked, he and Naruto were able to land multiple attacks and push Obito to his limit.
Furthermore, I think that Kakashi and Obito's use of Kamui might conflict with eachother. Kakashi first figured out that Tobi was Obito when he accidentally hit him with a kunai by teleporting it to the other dimension. This is an indication that if they were to use their abilities at the same time, there is a high probability that their teleporations would conflict. Thus, with all information, Naruto and Hashirama would just need to attack them at the same time, and they would likely get hit by the attack that the other person dodged.
Overall, I don't think Minato would bring much to the table. He is fast, but not as fast as Naruto (even with FTG). His most powerful technique is impressive, but not as impressive as Naruto's versions (Rasenshuriken and TBB). Minato is a genius, but I doubt his level of experience is anywhere near Hashirama's. Furthermore, Hashirama could sprout a poisonous plant wherever Minato throws a kunai. This would drastically limit his mobility and make FTG pretty muc useless.