If he's under 30 he can go for a year on a visitors visa, allows him to work and play
Once he's done the year and/or reaches 30 he comes under their quota system based on points. He can also be "sponsored" by an existing business which, simply put, increases his points. Sounds simple but is anything but, and has many pitfalls.
My son went out 4 years ago and "thought" he had complied with all requirements, was "sponsored" by his employers, and was quite legal, especially as he was paying Aussie Income tax , and even got a nice tax rebate at the end of year two.
Unfortunately however, the company "sponsoring" him went broke, no problem he quickly got another job (paying even better) and simply continued. A further year down the line and it transpired that the original "sponsoring" company had lied to him - they had done sweet FA - although they had taken his "contribution" to the costs of sponsorship.
So, legally, he had both stayed past his visa limit, and was working illegally. He was, potentially, up for imprisonment followed by deportation. Luckily he was able to prove that he had been told one thing whilst another was actually done, and argued that he could not be working "illegally" as he was paying Aussie Income Tax.
Based on those facts Aussie Immigration (which is a law unto itself) have relented, but only slightly. They issued him with a permit to stay and a permit to work, but he, sort of, cannot leave Australia, even to visit UK, as if he does he is not allowed back in for 3 years !!
Given those experiences, my advice would be to contact the Aussie Embassy and check, then double check, what is required, and any implications.... internet advice may well be totally wrong, and lead to problems later.
Having said all that... the boy loves it out there, we visited 3 years ago and, although the cost of living is very high (£8 a pint for "beer" that is undrinkable), wages were very good giving a high living standard. Things are going downhill a tad, economically, so perhaps the best times have passed.
It is certainly a fantastic country, with all sorts of places to visit, and very friendly people, but you do need money ... the poor are VERY poor, with very little social security it seems.
HTH