Board Thread:Versus Debates/@comment-30355627-20161030163643/@comment-25122992-20161211175226

Shin: Sasuke himself noted he hadn't have the full access to his powers due to overusing the portals to Kaguya's dimensions. Also, there were such factors as no prior knowlegde about Shin's abilities and Sarada who had to be protected from him.

Momoshiki: Neither Naruto nor Sasuke could use their strongest techniques since all of them are ninjutsu which were rectricted due to Momoshiki's abilities. Also, it's possible that Sasuke has lost some decent amount of chakra when he opened the portal again, the same way as Naruto lost his due to being captured by Momoshiki and his attempts to absorb it.