How about an Aus vs NZ contest?
Seems to be enough from both sides. 
All this is just ideas, i think it owuld be a interesting thing to do.
Since 3v3 seems the most played/playable gametype, 3v3.
Map random?
Conquest as the only gametype.
Default settings?
Say a 16 team competition? Or if not enough 8 teams? Half of each nationality.
Both country teams play vs the same nationality team untill the final, sudden death knockout.
So basically, the teams of each country play off to find out who is the best, then those play off for the Aus vs NZ title.
The match to somehow be shown live online?