I have been considering the best plan of attack on all the species. Here is my list. Vex: Time traveling robots with a large fan shaped head. Always shown in lines, making frontal assault unreasonable. The large head suggests that a head shot wouldn't do much. Attack from the sides of possible, while at an angle to the enemy. Two groups attacking would be ideal. Cabal: big guys, probably sporting heavy weapons, and armored to boot. Engage at a distance or behind cover with rifles. I imagine that there are weaknesses in their armor. Hive: expect hordes led by a noble. A marksman to kill the leader and machine guns to kill the horde. Spider pirates: I expect them to use rifles and swords, along with an occasional heavy weapon. Kill according to the greatest threat, as order doesn't seem to be their trait. All these are for a team of at least 5, though could be adapted to more or fewer. It is also based on speculation and should be treated as such.