Here is the full list of all 46 Trash Squad achievements.
Hire 15 mercenaries.
Destroy 1200 elements not including walls.
Complete the game in Nightmare mode.
Complete the game in Cannonade mode.
Collect seeds playing as Mud Thing.
Destroy 5000 walls.
Kill 50 bosses.
Kill 40 mini bosses.
Kill 5000 monsters.
Complete the game in Normal mode.
Collect robot parts playing as Welder.
Open 50 chests.
Kill 25 mini bosses.
Hire 5 mercenaries.
Kill 30 bosses.
Destroy 2500 walls.
Destroy 600 elements not including walls.
Kill 25 bosses.
Open 30 chests.
Destroy 400 environment elements except for walls.
Kill 10 mini bosses.
Open 20 chests.
Collect 2000 armour units in total.
Unlock 4 characters.
Destroy 300 elements not including walls.
Kill 1500 monsters.
Destroy 600 walls.
Destroy 500 walls.
Kill 1000 monsters.
Kill 5 bosses.
Open 5 chests.
Kill a chicken in the Composter.
Unlock 1 character.
Unlock 7 character skins.
Unlock 8 characters.
Unlock 3 character skins.
Unlock 10 character skins.
Unlock 15 character skins.
Unlock 3 skins for a single character.
Unlock 3 skins for each of 5 characters.
Unlock 3 skins for each of 10 characters.
Kill 10000 monsters.
Complete the game in Horde mode.
Complete the game in Elite mode.
Hire 35 mercenaries.
Achieve rank 2.