Many of the openings with "system" in the name are boring for that exact reason: they're pre-packaged arrangements of moves that have little cause or effect on how the opponent plays. The London is solid and unaggressive, leaving it to the other player to go wrong at some point. That being said, you can do most anything against it: b6/c5/Bb7, Bf5/c6/e6, c5/e6, g6/Bg7, etc. ...c5 with Qb6 can be useful to take advantage of the c1 bishop's absence, much like in the Trompowsky.
It isn't necessary to trade white's f4 bishop and it may get replaced by a queen from d2, pawn from e3, or other defender anyhow. What generally sets this opening apart is that ...e5 is out of the question for black, and again play on the dark squares is more effective than usual because white's bishop is away. If you're playing to win rather than draw, be aggressive with c5 and Qb6, or even a pawn storm on the queenside. The fianchetto is fine for the f8 bishop or it can go to d6 for the trade; e7 is viable too. Another option is chasing the f4 bishop with Nh5, especially if white plays e3 before h3 and leaves it without a retreat.
Is it just me or are these London System games kind of boring?
What do you play against the London System and why?
Are there any tips in playing against it? I heard that black should trade the dark squared bishops off. If this is what black is supposed to do, wouldn't it be a bad idea to fianchetto the dark square bishop like many black players do when they go into a Kings's Indian Defense against the London System?