Board Thread:Speculation House/@comment-71.17.68.254-20130907025506/@comment-3146930-20140126231347

It is possible that Grimm don't see each other as threats or competitors. It isn't even known if Grimm eat, considering how long the Death Stalker was probably in that cave. Based on that, there really isn't a "Food Chain" for the Grimm so they would have no reason to fight each other. What the Grimm do have however is a desire to destroy humans for one reason or another.

I also don't think that they are as smart as you are implying. They attacked the teams individually and some of their actions happened to help the other. For example, Ruby tried to attack the Death Stalker, but failed and ran away. The Nevermore then swooped in and launched a bunch of feathers. This could be interpreted as them working together, or it could just mean that the Nevermore had it's eye on Ruby (she did hitch a ride on it and we never know how). From there, the groups ran away together and the Nevermore crashed the bridge, separating them. From there the two Grimm attack those that they can attack, the Death Stalker goes for JNPR and the Nevermore goes for RWBY. It is also interesting that each Grimm attacked the team that had pissed them off, with Jaune and Pyrrha waking it up and Ruby and Weiss riding on the Nevermore's back, which we never figure out how.

To put it another way: The Grimm don't see each other as threats or competitors and just attacked those that had irritated them. If they happened to work together, it may have been unintentional as most of the times it seemed like they were working together, it involved them attacking an individual that they were already targeting.