Solo Giddy with AI head over to the plants side and start doing battle with those wildflowers again. For this achievement press Y to enter the space station mode and then when some enemies are grouped up hit RB and you'll go up and shoot a beam down. Vanquish plants with this ability. LB seems to reduce the cooldown on this ability so once you hit RB use LB to gain it back. You'll have this before your 200 normal vanquishes which also count while you're just shooting in this spaceship mode. Easy money.