Big Brother is... Sorry, not that Oceania.
Australasia Australia and the Pacific Islands. It's a political continent, because it can only reach the geographical definition of "continent" stretching its meaning until it reaches its plastic zone (or even fracture), because it's not a huge landmass but a collection of islands and atolls. On the other hand, Australia is considered a continent in its own right.
The islands are divided in three zones: Melanesia being the islands north and northwest of Australia (Papua New Guinea, Fiji, Vanuatu, Solomon Islands, New Caledonia, Australia's Norfolk Island, etc.); Micronesia, the micro-islands north of Melanesia (Federal States of Micronesia, Palau, Kiribati, Marshall Islands, Guam, Northern Mariana Islands, Wake Island, etc.) and Polynesia, with a lot of islands (New Zealand, Tonga, Tuvalu, Samoa, Cook Islands, Easter Island, Hawaii, French Polynesia, etc.).
You might also hear the term Australasia, this being Australia, New Zealand, New Guinea (the whole island) and some neighbor islands, including some of Indonesia. Sometimes Australasia is used the same way as 'trans-Tasman', to refer to Australia and New Zealand alone.
Regarding tropes, there are few of them here. Why? The islands have achieved independence only in the '70s and '80s (like Africa, they suffered from the same colonial syndrome). With the exception of the biggest three, every single country here has less than a million people, and most have less than 200,000.
- Papua New Guinea (Sometimes considered part of another region, such as Indonesia)
- Solomon Islands
- Australia, New Zealand, and Papua New Guinea