DMS Kakashi can't react to
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So Sasuke can blitz right off the bat if they're close, and DMS Kakashi doesn't have the durability RSM Naruto does too tank it.
If both Sasuke & Kakashi have PS up he can teleport out of the way of incoming Kamui Shurikens,
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Since Sasuke's PS has the inferior long range attacks compared to Kakashi's he can wait it out, since Kakashi's rikodou chakra will run out fast (1 chapter) also Sasuke is faster. The kamui shurikens hit Kaguya when she was unstable.
After busting Kakashi's PS, Kakashi won't be able to bust Sasuke's leaving him out of options.