A few suggestions. They throw some behaviors in with the formations, however, which may need to be 2 separate things.
First, an orbital formation.
This just assigns an entity, inside or outside the fleet, to the vessels. They then proceed to patrol around it, in 3D space, not just 2 dimensions, leading to, basically, an orbit. This is only ever assigned to escort vessels, because you don't really need traders just floating around aimlessly, so the vessels are then preprogrammed to attack any hostiles in the area.
Second, a trading formation.
Whatever shape you want, these entities just automatically flee in battle. They can be arranged, most likely, in a line astern ( <--- <--- <--- ) or a group of say 4 lines basically forming a selection of ship "blocks".
Battlefleet.
Yep. A fleet of ships. Starting with the flagship in the center. Arrayed in front is everything from the 2-10 slots, or something like that, and arrayed to the sides and rear of those are the rest of the vessels. These first 10 form a point (mothership), and then a hemisphere in front of that point. Basically, a wedge formation but without specific locations, just general areas to be in. Whichever's easiest to code. The rest of the vessels are placed mathematically: starting at 0 degrees in the circle formed when facing the rear of the command vessel, you place ships. Subdivide 360* among remaining vessels to determine additional placements by incremental changes in degrees. Thus, with 10 ships, they are spaced 36* apart around this initial formation. Once you get to, say, 18 vessels in this formation (20* apiece), you could start a new row behind and maybe even inside that one. Then, continue pattern until you come up with a point ship at the rear, directly aft of the mothership. This results in a globe of ships with the mothership inside, placed not at the exact center but towards the front of that center, to be close to the action if it's a battleship and yet still protected if it's not. Tactics are based on individual ships, honestly; however, if I'm not able to pick fighters vs bombers vs Titans to set up a different assault style, it's gonna be sit-and-shoot tactics. Minimum of maneuvering, steady gunfire. Ships support each other - if mothership targets vessel, all vessels target hostile vessel. Or if you, the player overlord of the galaxy, press F on something ... game over for them.
Lastly, fighter group formation. Also bombers.
This arrays like a flock of geese. You have the point ship (mothership or designated command vessel), 4 vessels in a pyramid formation slightly behind that, and spread out significantly. Behind each of those, you have 2 ships, spread towards the outside of this pyramid. You then have a staggered wall of fighters with a LOT of space between them. This makes sense - it is a tactical advantage to divide up hostile firepower. Plus you won't be wiped by missile area damage all at once. This works for bombers too. You would have maybe 6 ships or so inside this staggered pyramid formation, in order to have some follow-up to this wall, once you get out to 3 tiers or whatever.
-Not designed for heavy battlefleets, because it's more for slashing hit-and-run assaults. The tactics this would receive are to make assault runs on hostile vessels, not stick around and duel it out.
