It is obvious that you can't have a deck based on salamence ex PK... it wouldn't have any chance against the majority of decks. But I think that having a 2-1-2 or 1-0-1 line as a tech, or adding one in decks like sallygross would be a good choice.
What is the problem of discarding 15 or 20 cards from your deck when you already have a nice hand and a good setup?
your opponent will probably loose before you deck out...
150 each turn is just to high...
However and as you said slaking does really take care of salamence ex..., and crystal shard is also a big problem. You need to know when and how to play it…
Salamence ex: Risky to play, but very efficient