Could you clarify your question? If an opening can be "beat", then it ceases to be a playable opening at the highest levels. Last I checked, the Slav continues to be respectable and used by GMs. (the more famous + recent use of it was by Kramnik in 2006)
In the main line you listed, White can possibly "dull" out the game with the exchange variation (3.cxd5 cxd5). . To deal with this, Black usually varies the move order a bit ( ...e6 before ...c6)
All players are aware of slav defence but a few players know how to beat it.
Any suggestions?
slav defence opening.
(1. d4 d5 2. c4 c6)