Sorry if this is common knowledge but I haven't found an answer. Do characters on my team grant cover to the enemy if all other cover rules apply? Can my Maximus make it harder for my Luna to get a clean shot?
Yes. Check the reference guide, Cover entry: Both the Attacker and the Defender can add one to their Combat Rolls if they are Adjacent to a Blocked or Occupied space that is partially obstructing the Enemy’s Line of Sight. So it doesn't matter to whom the aristo belong, it's an Occupied space and it gives cover.
Thanks for the quick reply! I guess my d&d instincts to shoot through my tanks is too engraved in me.
However you should note that for this particular case, Luna's targets do not get the benefit of cover, so go ahead and shoot through your tank :D