Mina09

Australians also have the E3 visa available to them. He would need to meet the requirements (special skills) AND find an employer, but it's one of the easier routes to working in the US.
https://www.uscis.gov/working-united-states/temporary-workers/e-3-certain-specialty-occupation-professionals-australia

If he doesn't want to come permanently but wants to work in the USA just for the experience of living and working in a different country, a J1 visa for something like a summer camp might be an idea. It's doubtful that he's young to get any sort of permanent position but you said he wants to work in the USA, not live, so I'm thinking it's something he wants to do for the experience.
The USA doesn't have an equivalent of the work exchange visa that Australia has with the U.K. (where Brits and Australians under a certain age apply for the visa and are allowed to just go and find work when then get there). For the USA you need the job first and then the employer or organisation sponsors the visa.

Won't work - he will be ineligible to be sponsored for most of the specialized work visas like H1 (owing to his lack of formal education beyond high school). Possibly the only option may be seasonal work visas like H2 etc... if you can find someone to sponsor him before he comes.

Agree, student visa first, which may lead to a work visa.

He has no degree, very unlikely to get a work visa
Maybe he can try for student visa to study STEM degree in USA which may lead to working opportunity after graduation.