I am moving from Zurich to Valais and the municipality is asking for certificate showing how much social assistance I have received in Zurich (obviously none), anyone know where I can get that and what is it called in German?

I don't remember what the document is called, but I think you'd contact these folks?
https://www.stadt-zuerich.ch/sd/de/i...chsene/sz.html

In Kt Bern it was my regional district social help office that gave me a letter/certificate, not the municipality or canton. I wrote to them first to ask for the certificate, based on instructions provided by the municipality. The social help replied with a nice official letter that said they certify they have never had any contact with me. And they included a bill for about 20 Francs.

Something similar with document needed for naturalisation. I contacted Canton’s social service and they gave a link to a webpage where I requested it. Got an email (with letter attached) within an hour saying I had never claimed. There was a fee as well.

Was that in Zurich?