Killa Thrilla Trophy
Destroy 2500 airborne enemies
"Airborne" enemies are pretty much every enemy that you encounter in space. The only enemies that do not count towards this requirement are turrets, mines, and the enemies in platform portions of the game.
To earn this trophy, kill 2500 enemies throughout the game. Total kills are cumulative, meaning that your total kill count carries over every level and can be farmed in the same levels repeatedly if desired.
Below the spoiler bars are examples of some of the common enemies in the game that count towards this trophy:
(These are some of the larger airborne enemies in space.)
(These are some of the more smaller airborne enemies in space.)