Here is the full list of all 20 Clash of Robots achievements.
Level 3
Level 6
Level 9
Level 12
Level 15
Level 18
Level 21
Level 24
Level 27
Level 30
NEW_ACHIEVEMENT_DESC_1_11
NEW_ACHIEVEMENT_DESC_1_12
NEW_ACHIEVEMENT_DESC_1_13
NEW_ACHIEVEMENT_DESC_1_14
NEW_ACHIEVEMENT_DESC_1_15
NEW_ACHIEVEMENT_DESC_1_16
NEW_ACHIEVEMENT_DESC_1_17
NEW_ACHIEVEMENT_DESC_1_18
NEW_ACHIEVEMENT_DESC_1_19
NEW_ACHIEVEMENT_DESC_1_20