How to counter the Catalan?

I typically play 2...e6 after 1...Nf6:

usually  3...d5 and 4...Be7 , 5...0-0 and 6...dxc4 allows Black to get a decent position.

      If you like Benoni types of positions, then 3...c5 is a reasonable defense.

     Daniel King has a chessbase training video where he recommends the Closed Catalan for Black; i.e. Black keeps the pawn on d5 for awhile.

Personally don't think catalan is much for club players to worry about.  Modern Benoni quite lively, although white can play nf3 with english positions.  3...Bb4ch 3Bd2 BxB and if 4QxB d5 etc very solid and straightforward line. There are also straightforward open catalan lines where black plays to neutralise bg2 and play c5, i.e 3...d5 and 4...Be7 , 5...0-0 and 6...dxc4 mentioned above. 

Just think black needs to avoid the closed catalan where the skills gap between club player and GM, works more in white's favour. In many open catalan positions a Kramnik can work with subtle positional ideas to try put pressure on black, but the majority of club players completely clueless what should be doing. 

4... Bb4+ 5. Bd2 Be7 is also a relatively easy line to play.

Just copy cat.

Possibly helpful: Declining the Queen's Gambit

https://web.archive.org/web/20140626233841/http://www.chesscafe.com/text/hansen149.pdf

If white is so inclined can book up on g3 modern benoni from, for example, the Avrukh books. Top class players like Korchnoi also played this as white, so although the positions are lively, the fun isn't onesided in black's favour.