1...Nc6 can be played against any first move by White. You don't need to know a ton of theory, since there really isn't much theory that exists given that the defense is seldom played by GM's. It typically leads to lively, interesting middlegames. You might want to buy Play 1...Nc6 by IM Christoph Wisnewski. (The title is a bit misleading, since he recommends playing 1...d5 against 1 d4, and then usually following up with 2...Nc6.) A much older but good book is Complete Defense for Black by GM Raymond Keene and Byron Jacobs. The Keene and Jacobs book really does recommend playing 1...Nc6 against literally everything.
1...g6 against any White first move, as suggested by an earlier poster, is also a good debut. By favorite book on this defense is Winning with the Modern by GM David Norwood. A more recent book on 1...g6 is Tiger's Modern by GM Tiger Hillarp Persson. Persson's book doesn't really provide a complete repertoire, as it's primary focus is the move order 1 e4 g6 2 d4 Bg7 3 Nc3 d6. There is also a chapter on 1 d4 g6 2 c4 Bg7.
Originally posted by irontigranI assume you're referring to The Hippopotamus Rises by IM Andrew Martin. In the early 1970's, then-IM Andrew Soltis wrote a pamphlet in descriptive notation for Chess Digest called something like The Defense 1...P-QN3. In the booklet was a chapter on the so-called MacLeod System (...b6 ...Bb7 ...g6 ...Bg7 ...d6 ...e6 ...Nd7 ...Ne7). Soltis doesn't give much analysis here, but he does quote a game in which white puts pawns on c4, d4 and e4. I think I still have the booklet somewhere, so I'll see what Soltis says about Black's best play against that type of pawn center.
i just got the only hippo defense book out there.
but its missing a huge chunk, games where the C pawn goes to C4