There 3 types of visas for partners, each starting with a temporary visa stage, leading to permanent residency.
Visas Subclass 309/100 (Partner):
For an overseas spouse or de facto partner of an Australian citizen, Australian permanent resident or eligible New Zealand citizen (the sponsor), including same sex couples. Dependents may be included.
Visas Subclass 820/801 (Partner):
These visas are very similar to visas 309/100 above, but for spouses or de facto partners who already are in Australia.
Visa Subclass 300 (Prospective Marriage):
For you who are overseas and intend to marry an Australian citizen, Australian permanent resident or eligible New Zealand citizen. Once in Australia holding visa subclass 300, you might be eligible for subclasses 820/801.