The Plasma Storm expansion set contains 138 cards if you include the 3 secret rare cards. The copyright date printed on Plasma Storm cards is 2012, but the set was released in February of 2013. The most valuable cards in the set are the Pokemon EX cards (there are 12 of them!), the 3 secret rare cards, and the rare ACE cards.
Plasma Storm Set List
Complete list of cards in the Pokemon Plasma Storm expansion set.