hi there,
Been there, but not recently. But as far as I know, if you can do the sphair stuff you will be fine for the Skyguide tests. Anyway, my suggestion is to just go there, the tests are not that bad as the sphair one's I think. And the level 2 tests... Either you can or you can't do them, the feeling after them is anyway bad
If you can read german, go to flightforum.ch (biggest aviation community in switzerland). Use the search function and search for "Eignungstest" in the ATC section. There you'll find multiple threads about this topic.
cheers,
tobi (zurich atc)