I don't travel to the Alps to ski, but I do travel to hike or sight see in the high Alps. Because I am familiar with some of the regions, I use a particular technique to get more information on the cableways. It shows the timing but also how the cableways fit in the landscape and geography.
You may have picked a time when many skiing facilities are shut down.
When planning a trip in Spring or Fall, I use the SBB timetable linked by Lucas for a quick way to check to see if the main cableways and alpine scenic railways in the region of interest are running. Typically they stop running sometime in April or May and start up again for the hiking season in mid-June. This way to check is quick for me for checking a few individual transport facilities in familiar regions, but tedious if you do it for many different stations. It works best if you know the names of the stations, which you can get from the map I have linked below. And, it is useful to understand what times of day the specific facilities shut down for the night
This map shows cableways and mountain transport if you turn on the proper choices in the menus under traffic and zoom in:
map.search.ch/?pos=788372,154866&z=12 8&poi=bergbahn,haltest elle,viasuisse,zug
I have done so for the region near St. Moritz and Pontresina.
If you click on the icons for the stations, you get a brief timetable for near time transport to/from that station/stop, and you also get the name of the station for use in the SBB timetable when you mouse over the icon.
There are also specific web sites for the various Alpine regions, with a wide range of information including details of transportation, but I don't know the ones for the regions you are interested in. Lucas gave you a couple of links that should be helpful.
I just noted this thread:
Alpenrose has provided quite a bit of detail on alpine transport, mainly in the Jungfrau Region, but is is valuable for showing the typical availability patterns in the Spring. It gives a good perspective on the typical issue for that time of year.
There is also a specific comment on St. Moritz.