I think 2 tops. Because even someone like Obito with his massive reserves lost control of the 5 tails while controlling six out of nine.
a
Obito controled them by usng outerpath & Gedo
OP askng abt Sharingan
How much bijuu's can Sasuke control at once?
its shown madara can control kurama with a 3 tomoe sharingan.
I think sasuke can enslave up to 2 or 3