As far as I know, Wallaby Way is not a street name in Sydney. It is quite possible that there is a Wallaby St/Rd/Ave etc somewhere in Australia, but the visual depiction of 42 Wallaby Way, Sydney in Finding Nemo is not realistic. From looking at the view that was depicted from the window of the dentist lab, it looks like they based the location from the real life view from Taronga Zoo (Sydney's main zoo) which doesn't have any major road or businesses or houses on the foreshore in real life.
In fact, on the north side of Sydney Harbour when looking south (just like the depiction of Wallaby Way in Finding Nemo) there is quite a lot of bushland and there is also Sydney Harbour National Park, which is very rugged and not urbanised.
Sydney is quite a large city and it is possible that there is a street or road or avenue that starts with Wallaby, but probably not "way" and the way it was depicted in Finding Nemo is totally fictional. In other words, there isn't a dentist called Dr Sherman with a business address in Wallaby Way, and it definitely doesn't have harbour views or waterfront access.
Also, Sydney has about 300 suburbs all with their own individual names, so to be located in Sydney, it would have to be located in the Central Business District (where all the tall skyscrapers are).
By the way, the answer above which discusses all the streets with "Wallaby" in their name - those places are not in Sydney. They are all located in other country, regional and rural towns, hundreds of kilometres from Sydney.
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I've lived in Sydney all my life, and Finding Nemo is one of my favourite Disney movies