I don't think you can really do under cranking but there are Frame and Interval recording modes available when in MP4 mode. This video does a quick demonstration of time-lapse recording - https://www.youtube.com/watch?v=akeiQ-GzW20
No as far as regular motion. One of the things I dislike about the C200 it can only shoot 23.98, 24.0, 25, 29.97, 50, 59.94 and 120 fps. No VFR, no ramping although as Dustin notes, you can go sick with time lapse but that's not the same. Even my lowly HPX-170 had true VFR. I feel this was on oversight by Canon unless there is some compelling engineering reason why one should not be able to select a 16 or 28 fps setting? I think we put this request into my "open letter to Canon wants for firmware upgrades" thread.