Defense to Strong Pass Systems
Strong Pass systems are very rare, and as a Highly Unusual method you will never encounter one outside extended team play or without notice. 

In extremis, adopt your Strong 1C defence by substituting a 1C call for a double of a 1C opening, and warm up the Double cards if opponents open a fert (any call besides Pass that is definitely limited) instead.

Anecdotes and alternatives from BridgeBase.com:


  When I met it years ago, I played that a One Spade overcall said "I am
  present at the table". The next player bid 1NT, alerted as Stayman.


and 


  "Need" is a strong word, but it's always a possibility to consider
  making your "opening bids", especially in the majors, be more akin to
  overcall strength than full openers. This is tougher for the minors
  because you might need to make convenient minor full opening bids and
  it can be harder to distinguish them from overcall-style openings.


and


  If they 'open' a pass bid as much as you can as fast as you can. If they open a 
  fert be prepared to double them lots with balanced
  hands and your overcalls are more like opening bids with shape. If
  they open with something else then use your generic meta defence and
  bridge principles.


and even:


  Use an anti-fert over the fert.
  1H  = 0-8,
  1NT = 0-10.
  Its a lot of
  fun.