Madara stated that the perfect susanoo power is comparrable to a tailed beast.But sasuke doesnt know how to use perfect susanoo,since he just started using EMS(i think his EMS isnt at full power since sasuke left the hide out while his eyes still needed more rest).So when Sasuke will learn to use perfect susanoo and gains experience using it,then he will be able to defeat Bee,high-difficulty.But since right now in the manga,sasuke doesnt know how to use the perfect susanoo,so he doesnt have anything to match Bees power in TBT(tailed beast transformation)so he would lose period.
1.For those idiots who said that TBB(tailed beast ball) is weak,let me let you something .TBB has the power to destroy mountains(shown during naruto bee vs tobi and the tailed beasts) and sasukes susanoo rib was broken by As punch,so its clear that susanoo can be destroyed by TBB.
2.When sasuke and bee first fought,none had any info about one another.Sasuke was an MS user and bee was an perfect jinchuriki,so its illogical to say that sasuke was at an disadvantage.But now they both have info about one another and each others techniques so its going to be an fair fight.Actually sasuke did have a bit of an advantage because he had Karin,Juugo and Suigetsu at his side while bee was alone.
3.When sasuke fought Bee,sasuke only survived because of Karin and Juujo.Sasuke literally had his chest blown off by bees larient.And please dont say that Suigetsu could stop TBB or TBT,its very idiotic.Suigetsu is from the hozuki clan so phyical attacks are usually useless against him or have a lower effect on him.The TBB just had a lower effect on suigetsu because of is abilities,but the effect were tremendiously powerful enough to nearly kill him,so he didnt even stood a chance against the TBB.
4.Bee is superior than sasuke in taijutsu,and genjutsu doesnt work against him,and as for ninjutsu.Bee can possibly escape amaterasu as he has already done it before successfully,susanoo arrows will prove a probem but probably not enough to take bee down.Bee is incredibly fast when he is using the eight tails chakra.
Sasuke does have the potential to defeat Bee,but right now he cant.As I said before Sasuke needs the perfect susanoo.No offence sasuke fan boys,but sasuke is a bit cooky,arrogent and underestimates his opponents(not a sasuke hater).
At the time of sasuke and bees fight,sasuke only knew how to use Amaterasu and Tsukiyome(dont argue about this ability,its my own perspective).But at the five kage summit he learned to use the susanoo,and blaze release.This was the only improvement until then,so sasuke fanboys are wrong when they say that his taijutsu and other skills had completely increased.At the time of the battle with bee,sasuke wasnt 100% well phyically because of his battle with Itachi,so its just an illusion if they think that sasuke was on top of his game against bee.But THIS DOESNT MATTER BECAUSE OF THE ASISTENCE O JUUGO,KARIN AND SUIGETSU.