Yes, there is some counter play against Kha'zix. Crowd control is effective, as with any melee DPS champ (though less so against a KZ building some survivability, which he should). Clumping together works to stop some of his damage, but there are a few reasons that this is not foolproof. First, a 4v4 fight will have SOMEONE that is slightly isolated from their team, and his leap and ult give him all the tools he needs to get to them. Second, he can and should be ganking bot lane a lot.
And finally, and I think this is really underestimated: the game teaches you that clumping up is bad. You'd think that having Brand and KZ on the same team would be bad, because it's basically anti-synergy, but what you're actually doing is setting up a situation where you can take advantage of the counter-play to Brand or KZ, but not both.
I've played the mirror match (top lane) against Tigerbite with KZ three times so far, and it seems like we've settle on the same build (More tanky core: defensive boots, last whisper, frozen heart, hexdrinker. Less tanky core: CDR boots, brutalizer, LW, chain vest, hexdrinker). Regardless of the winning team, both KZ seem do well.