The hosts have already wrapped up the series after winning a rain-hit match in Brisbane by 29 runs and then in Sydney by 13 runs.
Pakistan made three changes with captain and wicketkeeper Mohammad Rizwan apparently resting and Agha leading the team for the first time.
Sahibzada Farhan is set to move up the order and open alongside Babar Azam with Haseebullah Khan keeping wicket.
Seamer Jahandad Khan comes in to make his debut in place of Naseem Shah.
Australia named an unchanged side.
Teams
Australia: Jake Fraser-McGurk, Matt Short, Josh Inglis (capt), Glenn Maxwell, Marcus Stoinis, Tim David, Aaron Hardie, Xavier Bartlett, Nathan Ellis, Adam Zampa, Spencer Johnson
Pakistan: Babar Azam, Sahibzada Farhan, Haseebullah Khan, Usman Khan, Salman Agha (capt), Irfan Khan, Abbas Afridi, Shaheen Shah Afridi, Jahandad Khan, Haris Rauf, Sufiyan Muqeem