Here is the full list of all 9 Hover Junkers achievements.
Revive your shipmate 3 times
Dunk some junk in a basketball hoop
Hit all the targets in target practice
Collect all of the capsules
Hit all glass bottles in the shooting range without missing.
Complete an 8 player match without anyone dying.
Try out every ship
Travel to each map in a single match
Hit another play from very far away