A number of camcorders do slow motion. My Panasonic HC-V750 (UK), now replaced with the 770, will do HD and 100fps Slo-Mo (the US version does 120fps) and will transfer down to 200fps (1/4 speed) in the playback mode while creating a second video file. Obviously the playback of these two files will give the slow motion effect. The original slo-mo recording is frame accurate and the slower version is created by doubling up each frame. The files produced are in MP4 format.
You will need to look at the camera specifications to find the right camera for the job. Post production using your video editor will give you slower copies of the original but with the addition of extra frames.