The spectrum of skill and well-roundedness can be difficult to tackle. I honestly think both CG and C9 have less weaknesses than TL in the sense that they're more well-rounded, but they're just not as good player-wise. You beat CG and C9 by simply being better than them instead of devising some specific strategy targetting their team.
A team like RNG is the perfect example. No one's going to argue they aren't good, but there are definitely gaping holes in how they play the game which can be exploited (over-reliance on bot lane, sacking solo laners). And when good teams have these, it sparks a lot of discussion, because they're expected to do well but you can clearly see where it can go wrong.