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