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