Here is the full list of all 27 Gear Up achievements.
Destroy 20 enemies with the Grayhound (saws).
Destroy 10 enemies with the default starter cannon.
Drown in the water at least once.
Repair 30000 armor in lifetime.
Repair (1250) armor in one round of a team game mode.
Destroy 1500 enemies
Win 20 deathmatch rounds.
Destroy at least seven different opponents in a team game mode.
Assist in capturing at least 20 conquest towers in a single round.
Win 20 team deathmatch rounds.
Win 20 conquest rounds.
Back playing after more than one week of Gear Up absence.
Win a TDM round overwhelmingly, with a ratio of 4:1 or higher.
Win a Conquest round overwhelmingly, with a ratio of 4:1 or higher.
Killed a deserting enemy
Destroy 100 enemies
10 kills in a row
Recieve 500 damage without being destroyed in a round.
6 kills in a row
Destroy 75 enemies
Capture a conquest tower together with 3 or more teammates.
Destroy 50 enemies
Win 3 conquest rounds.
4 kills in a row
Destroy 25 enemies
3 kills in a row
2 kills in a row