Switzerland - diplomas, references, recommendation or proof of good conduct

Do I need to send diplomas with my application?

If specified in the advertisement, include a copy of your highest-level diploma with your covering letter. However, never include this if you apply spontaneously. Hand it over at your first meeting at the company.

Should I supply references, letters of recommendation or proof of good conduct?

You should be able to provide names of people who can act as referees, if asked. Letters of recommendation are rarely used. If you need proof of good conduct, this is usually mentioned in the job announcement.