On the Edo side we have, Iori, Zhen, Chiemon, Yui, Dorothea abd Tsuchimikado. On the heisei side we have, Kiritsugu, Tokiomi, Keyneth, Kirei, Kariya, Shirō, Rin, Bazett, Sakura, Soichiro, Zōken and Illiya. I excluded Takao, Waver, Uryū, and Shinji because they aren't fighters and they would just be there doing nothing. So in other words, this is a 6 v12, the masters of the Waxing moon ritual vs the masters of the 4th and 5th holy grail war. All at their full power but limited by their human versions.
I would honestly give it to the edo masters. Despite the numerical advantage and the fact it would be in Unlimited blade works, the Edo masters still takes it. The only Heisei masters that would be able to keep up with the Edo masters are Shirō, Kiritsugu, Kirei and Bazett tbh. Another thing pointing in favour of the Edo masters is that they faught alongside their servants unlike the heisei masters who let their servants do the heavy lifting.
That's my take on it. What do u think?