I've upgraded to kde5, before the upgrade kde telepathy work without problems.
I've the telepathy-gaze/gabble/mission-control-5 package but in the settings in kcm this chats are not listed.
i don't know if facebook it working at all these days, because they closed ther API. I know that there are people that planed to workaround it. For skype you need to have skype installed but googletalkshould workout ofthe box with telpathy-gabble.
I've skype installed but as you can see in this screen they are missing
Google talk has been dead for awhile, Feb 23, you can't find it at the playstore either.
Perhaps kde telepathy is using some kind of third party support for google talk or it switched to google hangouts which is the replacement for google talk.
Facebook is banned on my phone (the best battery, memory, resources, eating app on "any" phone, with whatsapp right behind it ) and computer so I can't help much with that (I am not into the social media crap)
I haven't used skype in a very long time, pershaps a look thru the forums here can help.
Not much I know.