[Tugay]

In the original new games you can fight like this.
So for example I'm at Combat Fields, ev-ing my pokemon's speed stat by fighting poliwhirls with good rod. To make 200 ev ı need to fight 50 times if ı'm using macho brace.
But if ı would fight a horde of poliwhirl (like fighting a npc that has 5 poliwhirls) ı would only fight 10 times to make 200 ev s. 
In x and y, there were some special places, that you can fight with horde encounters.. The reason they add this system was the same, to make ev-ing easier, I guess.