Today while playing TF2 on a lighthearted (but experienced) game server, a large majority of the other team went spy and proceeded to mass revolver everyone. Their aim was quite accurate and was able to consistently kill many players that got within medium range.
Now obviously the hard counter to spies is the pyro, however they could gun down anyone who got closer than 30 feet away. And, since the pyro's effectiveness drastically decreases with range, the spies could pick them off before any burninating happened.
Speaking generally, when another team decides to purposefully class rush to gain the upper hand, what's the best way for my team to respond to that class imbalance? Would I want to purposefully create a class imbalance on my team to respond to theirs?