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