Pirc Defense

     Pirc is perfectly fine and it is used from Black players in "must win situations"(as stated by Svidler).It has no similarity at all with King's Indian defense  and even if it had, that would be a perfectly good reason to play it.

    The problem is that Black has a lot of options at his arsenal so showing you how to play against it in one post is  impossible.

     The easiest to understand because of it's straightforward plans is the 150 attack(easy to understand doesn't mean easy to play though , nothing is easy in chess).

That's the 150 attack , called that because it was very popular among players rated 150 in the British system(around 1800 ELO).

    Nothing difficult till now.Ng1 naturally developed on f3 , Bc1 to e3 and Qd2.

White's main plan is to play Bh6 , exchange the important Bg7 and then launch a k-side attack.Note that White has the option of castling on either side.

      It is true that Black's play was quite weak in the above games but both players were close to 2400 FIDE!

     It is not always easy attacks like these and don't do the mistake to believe that Black is without counterplay.

One thing is sure , in this line the best player will win(actually this is the case for almost every line except lines that are overanalysed and the better prepared player might win).If you want I can send you  Summerscale's "Killer Opening repertoire", a book that deals with it exclusively.If you ignore the misleading title (there are no killer openings or repertoires , these are fairy tales and advertising tricks for ignorants) , it's a book that has everything you need to know about the line and focuses on games and not on theory(it's a line with not much theory anyway).I wouldn't call that book perfect but it's a good starting point.Later , when you improve , you might need a much better book (like the ones IMPoucin recommended).Message me if you are interested.