Just a quick addition: Only base game missions are needed for this achievement. Since I didn't know which ones were in the base games and which ones came with DLC, here is a quick list of missions needed
Training Mission
- All 5 (giving
achievement)
Battle Mission
- Normal on Tatooine
- Hero on Tatooine
- Normal on Endor
- Hero on Endor
- Normal on Sullust
- Hero on Sullust
- Normal on Hoth
- Hero on Hoth
Survival Mission
- Tatooine
- Endor
- Sullust
- Hoth (the normal one, not the one in Ice caverns)
To be sure, you can snap the achievement. When you complete one of these, the completion percentage will grow by 6%