There are many problems with a Cat deck in PvP, and many more when the AI is playing it. The biggest problem is how rarely the AI will use the Cats' abilities. The AI needs 200% of the quanta needed for the ability to have a 100% chance of using it every turn, but then there are more factors that may prevent it from activating them.
As for the normal weaknesses of a Cat deck, yes, CC really wrecks them. Dexterity helps a -ton- with this in mind, but you still need both PC and hard CC to supplement it. While Entropy has both, the hard CC is Chaos Seed or Pandemonium. Seed is weak per card and Pande kills your own Cats, but in Death we only have slow CC via Plagues and Viruses. Slow CC means an Oty won't even die from one cast since Devour adds 1 HP per use, and the likes of Ulitharids will be Lobotomizing many times before death.
The only offence that grows well with Cat is Vulture since Skeletons from Boneyard both lose to PC, mass-CC and any shield. It's not worth packing Nightfall for them at -all-. Now it may seem silly, but the alternative to Vultures are Bone Dragons. In addition, the most consistent damage in Death are Poisons and Arsenics. Balance the deck out with all of this in mind.
You're right to keep at least 3 Bone Walls as it's the best rush-counter shield (can't be PC'd). With all the above in mind, you'll want to try to max out on Chaos Seeds and Cats, and choose between either Poisons, Bone Dragons or Vultures. You may find a combination of the first two is the most optimal. For PC we only have Butterfly Effect, and it's the best we can do. Discord only helps for a few turns, and that's not enough when your deck is slow. Making the deck a trio is a terrible idea since it's a very dedicated duo both quanta- and card-wise.
