So, Nintendo Australia confirmed both Gold and Silver Mario for May 30th in Australia and New Zealand. Silver is EB exclusive and Gold is Target exclusive. The only Target in New Zealand is a furniture store so I asked EB since they usually get store exclusives and they have silver but no gold, then I asked JB HiFi since they've previously done some of the Pokémon Mystery Gifts and they reckon it's an EB exclusive. I've also contacted other electronic stores that stock Nintendo products and so far one of them has emailed back saying they do not stock amiibo at all and I'm waiting for other stores to get back to me. I've even contacted Target furniture just for good measure.
Once I get the rest of my emails answered I'm gonna write to video game media about how Nintendo Australia has a bad habit of saying things that aren't true. I was going to write to Nintendo Australia but they still don't have a contact email.