Here is the full list of all 18 Trash Pit achievements.
Destroy 10,000 robots.
Destroy 500 robots in a single life.
Destroy 20 or more robots with a single explosion.
Let a boss robot stay alive for over one minute.
Reach a x100 multiplier without trampling any robots.
Reach a x100 multiplier without firing your weapon..
Dash through an enemy 10 times without letting your dashes charges fully reset.
Destroy 10 robots with a single dash.
Destroy 5 robots with a single scatter bullet.
Destroy a boss robot before any other robots are destroyed.
Finish a round in under 10 seconds.
Destroy 1,000 robots.
Destroy a robot within half a second of it landing, from more than 10 tiles away.
Regain a x100 multiplier after losing one.
Get a chain of 4 grenade explosions.
Destroy 100 robots.
In a round, destroy 10 robots within half a second of them landing.
Destroy 50 robots in a single life.