How to combat Cascade in Commander
So cascade is good because it is a powerful card advantage engine. This is why Bloodbraid Elf is banned in Modern and Shardless Agent has made a tier 1 deck in Legacy. 

There are a few strong counters to cascade. My favorite it Teferi, Mage of Zhalfir. Since they can only cast spells at sorcery speed, they can never cast the cascaded spell. Other spells like counterflux can counter all spells on the stack. 

Considering it is commander, you will probably need a collection of cards like this to fight against cascade. However, considering the problem is the commander, honestly just packing more removal for it, such as go for the throat, swords to plowshares, flame slash, etc is your best bet