You can do this is in Private Match by yourself. There are 12 Skillshots over the 6 maps.
TURBINE Blood Bath - Toss an enemy into the Juicer on the Turbine level. The Juicer is the fan on the roof in the center. Just Kick an enemy up there.
POWER PLANT Ground Chuck - Fling an enemy into the Grinder on the Power Planet level. Very easy. It's right in the center of the map.
JUNKYARD Man Crush - Crush an enemy with the Smasher on the Junkyard level. It's at the bottom. Just kick or Leash an enemy through it and it will automatically crush them.
Fish Chow - Send an enemy into the waterfall on the Junkyard level. The secret here is to just get enough kick to get them into the water but not so much they die from smashing into the back wall.
DEAD ROCK Not In Kansas - Fling an enemy into the tornado on the Dead Rock level. Kick or Leash someone through the large center tornado. Simple.
Nom Nom Nom - Feed an enemy to the Dinosaur skull on the Dead Rock level. Again easy. Just kick someone into the large Dino skull and it will smash them.
WATERWORKS Blood Fountain - Push an enemy into the river on the Waterworks level. The water is under all the platforms so just kick someone in there.
Royal Flush - Flush an enemy down the water tubes on the Waterworks level. There are water flow pipes on each of the platforms so just kick someone into one.
GRAND CENTRAL Midnight Express - Kill an enemy by flinging them in the monorail's path on Grand Central level. The only really hard one. The monorail runs the back length of the map back and forth. The monorail actually has to hit and crush the enemy so it's all about timing.
Make A Wish - Electrocute an enemy to death in the fountain on the Grand Central level. Just kick someone into the center fountain.
Meatspin - Propel an enemy into the revolving door on the Grand Central level. Kick someone into the revolving door. Make sure the Skillshot comes up as I got Graffiti for most of the kicks.
Flattery - Flatten an enemy with the elevators in the Grand Central level. There are 4 elevators surround the fountain and revolving doors. Kick someone into the shaft and then Leash the elevator down on them.