Collusion and things like collusion are of course not allowed. Around the edges, some cases are hard to decide. Best course, is no communication during recruiting - although that is a sad thing. Would like to be able to heckle, but the line between heckling and signalling is hard
There are lots of old threads on this.
In terms of battles, I think battles are always ethical - absent collusive etc behavior. A battle initiated in your team's interest is ethical. No question.
On the other hand, not all battles are smart. Only battle when there isnt a guy just about as good available without a battle. I try hard to lean against in-conference battles. Does not mean that I never do - I do now and then. but, if I can get another guy without battling in conference or if I have a roughly equal choice between battling in and out of conference, I will go out.
Growing the conference $ and getting along within conference in the interest of avoiding future payback battles is a good thing.