If you have the colony this and the two similar ones can be done in one game (although it may take a while).
Leader: Colony
Map: Fort Jordan
Difficulty: I used Normal but this may work on other difficulties as long as the AI doesn't get "smart" about it
Enemy: I used random and got the colony which worked out for me but other leaders may work.
Tactic: first of all grab all the bases except the furthest 2 from your starting map. Next earn leader points to unlock combat repair. Now all you need to do is set up each base with enough turrets to stay alive, post up some units om either slope of their base, and put either elite rangers (for the anti-infabtry achievement) or hunters (for anti-vehicle) in the garrisons of the teleport pad in front of your base (where the enemy will come out of. Also post up some Reavers there for the anti-air achievement.
Now you can leave your game running and what SHOULD happen is that the enemy will just continuously funnel their infantry, vehicles, and air through their teleporter and into your meat grinder. And with the combat repair, on normal, you shouldn't lose any troops even if you walk away from your game for a couple hours. Also works for getting the hunter captain taunts as you can put him near the slope of their base and keep taunting enemy troops as they go by.