Here is the full list of all 21 Pressure Overdrive trophies - there are 21 bronze.
Let a Sucker suck at least 10 pressure pills before destroying it.
Finish a level without driving on 'low pressure'.
Defeated 1,000 enemies.
Got in love touch with 10 enemies.
Defeated 5 enemies with one strike.
Finished a level without taking any damage.
Had a Spatank drag the buggy with a grappling hook for 30 seconds.
Defeated 20 enemies while a powerup was active.
Finished 20 levels in Endless mode.
Finished 10 Hornets with the railgun without missing once.
Finished a level with the buggy at maxed-out hull.
Finished a level with a buggy at maxed-out pressure capacity.
Finished a level with a fully upgraded Teslagun and Tesla secondary.
Finished a level with having activated underbody or rear explosives for 20 times.
Defeated all enemies on a level (Tutorial excluded).
Defeated the Riverbed Boss in Level 11.
Defeated the Castle Boss in Level 22.
Defeated the Underground Boss in Level 33.
Finished the campaign on the Easy difficulty level.
Finished the campaign on the Normal difficulty level.
Finished the campaign on the Hard difficulty level.