All of these skillshots can be done in a private match by yourself, for the achievement it only wants the original skillshots from the original maps, it does not require you to do the skill shots from what was the dlc maps.
Remember once you have done all the skill shots for the map let the enemies' kill you and then return to lobby otherwise they will not save!
Dead Rock:
Nom Nom Nom-kick enemy into the T-Rex skull
Not in Kansas-kick enemy into tornado in center
Grand Central:
Make A Wish-kick enemy into the fountain in centre of the map
Meatspin- kick enemy into rotating door to left of spawn
Flattery- kick enemy into any elevator shafts surrounding the rotating door
Midnight Express-kick enemy into the passing train at the back of level, what I did for this one is get the wave down a little bit, so you don't get shot too much then watch the train and time it and how long it take and just kick an enemy out with a single kick and they should float just long enough for it to be hit
Junkyard:
Man Crush-kick enemy into big car smasher at the bottom
Fish Chow-kick enemy into waterfall at the top of the map and have them flow down to bottom
Power Plant:
Ground Chuck-kick enemy into big grinder
Turbine:
Blood Bath-kick enemy into the fan in the middle of the map, just kick and the fan will suck them in
Waterworks:
Blood Fountain-kick enemy into any of the green liquid river that leads to turbine in middle
Royal Flush-kick enemy into green liquid coming out of the pipes
Any questions just ask.