Reddit has a summarized sentense that says pretty much everything about this achievement:
"Kill 15 Jolting Jacks while they are on rooftops using either Frag Grenades, Acid Bombs, or the upgraded M1897 Trebuchet in 1 match"
So it is important to mention that this cannot
be done with the wraith fire!
The M1897 is a wall buy weapon available at Green House Backyard.
Helpful elixirs include equipped mint (replenish grenades), cache back (max ammo) and the
timeslip perk that speeds up grenade generation (in 4th slot increases even more).
Most often the jumping jacks spawn on rooftops at the start of the round and you will have to be quick, since they will eventually drop down.
This achievement can be done in casual difficulty.https://www.reddit.com/r/CODZombies/wiki/alpha-omega#wiki_tr...
If you would like to know more, there is a fully described solution over at truetrophies:https://www.truetrophies.com/t261951/its-a-tossup-trophy