How Do You Combat a Fianchetto?
I don't think the fianchetto is something you need to fear in itself. You can just develop normally and be fine. If you are extra concerned, you can block the diagonal and then try to fianchetto opposite your opponent in order to trade off the bishops, or you could establish a center pawn on the same diagonal as the fianchettoed bishop and have it reinforced with another pawn. Very abstract of course, but so was the question.
btw GSHAPIROY's fourth variation is weak. 3...e6 and it's clear the White B does not belong on c4. 1.e4 b6 2.d4 Bb7 3.Bd3 e6 4.Nf3 (intending to put a pawn on c3, not a knight) is the best way to meet the Owen's.
i knew the question was a bit vague without ex's. but 'establishing a pawn on the same diag and reinforcing it' helps. That helps GreenCastle.
You could also try to play some games with a fianchetto yourself, and see how your opponents deal with it 
If you want to stop a bishop, you need to close its diagonal, it does not matter whether it is a fianchettoed bishop or not.
Just develop normally and you should have a decent position.
Also, the move g6 creates weaknesses on f6 and h6. If you can swap off the bishop (or get rid of it some other way, even tempting black to swap it for your a1 rook is possible in some positions), these holes can become inviting for knights, queens, even pawns.
I don't think the fianchetto is something you need to fear in itself. You can just develop normally and be fine. If you are extra concerned, you can block the diagonal and then try to fianchetto opposite your opponent in order to trade off the bishops, or you could establish a center pawn on the same diagonal as the fianchettoed bishop and have it reinforced with another pawn. Very abstract of course, but so was the question.
btw GSHAPIROY's fourth variation is weak. 3...e6 and it's clear the White B does not belong on c4. 1.e4 b6 2.d4 Bb7 3.Bd3 e6 4.Nf3 (intending to put a pawn on c3, not a knight) is the best way to meet the Owen's.
Why is it weak? 3. ... e6 does not help support d5 yet. Suppose white plays 4. Nf3. If 4. ... d5, 5. exd5 exd5 6. Nxd5 or 6. Bxd5 puts black down a pawn.
11. Bh6 does not force the exchange of bishops, because he can put his bishop on h8.
I don't think the fianchetto is something you need to fear in itself. You can just develop normally and be fine. If you are extra concerned, you can block the diagonal and then try to fianchetto opposite your opponent in order to trade off the bishops, or you could establish a center pawn on the same diagonal as the fianchettoed bishop and have it reinforced with another pawn. Very abstract of course, but so was the question.
btw GSHAPIROY's fourth variation is weak. 3...e6 and it's clear the White B does not belong on c4. 1.e4 b6 2.d4 Bb7 3.Bd3 e6 4.Nf3 (intending to put a pawn on c3, not a knight) is the best way to meet the Owen's.
Why is it weak? 3. ... e6 does not help support d5 yet. Suppose white plays 4. Nf3. If 4. ... d5, 5. exd5 exd5 6. Nxd5 or 6. Bxd5 puts black down a pawn.
First of all, what you wrote is false. Simple counting issue: White has three guys attacking d5 and Black has three guys defending d5 (pawn, bishop, and queen).
Secondly, even if I don't intend to play ..d5 next move and would rather play a move like ..Bb4 or ..Nf6, the move ..e6 does help support d5. The pawn is now diagonally contesting d5.
Thirdly, even if I never intend to expand ..d5:
It seems that bishop is always there, looming over you, ready to swoop down on your unexpecting pawn or other minor piece, perhaps ready to trap and eat your rook, after the knight in front of it attacks an important piece or Queen.
Is there some general advice on how to combat a fianchetto'd bishop? i don't know, fianchetto on the opposite side? (seems this takes too long) Get him to block his bishop with a pawn? (seems far fetched)
Any general advice?