In this game there is no need to rally. Instead just organize your alliance comrades to attack at the same time. Our battle system will automatically involve all ships in the same area when a battle begins.
Alliance leaders and rank 3 members can also create "Custom Legions" in the Alliance - Legion screen. These are like small battlegroups that other alliance members can join and they will provide you a private chat and place to share coordinates. Custom Legions can be useful to help coordinate your operations!