Here is the full list of all 17 MOBILE SUIT GUNDAM BATTLE OPERATION 2 achievements.
Rank up to Rating D.
Get promoted to Private First Class.
Defeat a rival.
Complete "Exploring the base camp" training.
Acquire 10 MS.
Sortie into battle 10 times.
Get promoted to Lance Corporal.
Get promoted to Corporal.
Get promoted to Sergeant.
Get promoted to Master Sergeant.
Rank up to D+ Rating.
Rank up to Rating C-.
Rank up to Rating C.
Rank up to C+ Rating.
Rank up to Rating B-.
Rank up to Rating B.
Rank up to B+ Rating.