In reply, Pakistan showed little resistance in 19.1 overs, losing Imran Nazir lbw to Starc for one in the second over.
Nineteen-year-old pace sensation Cummins bowled the third over and struck twice in five balls, removing Mohammad Hafeez, caught at cover for nine, and Shoaib Malik bowled for a duck.
Starc took the key wicket of Kamran Akmal for a duck and Umar Akmal (two) and Nasir Jamshed (17) followed as Pakistan slumped to 6-36 in the 10th over.
Yasir Arafat made 15 and Umar Gul (three) while Abdul Razzaq (13) was run out by Australia's 41-year-old spinner Brad Hogg who also claimed 1-11 off four overs.
Earlier, Warner hit six sixes and Watson was no slouch either, heaving five deliveries over the rope in a remarkable turnaround from last Wednesday's opening game when the Australians were dismissed for 89 and hit no sixes.
A highlight of left-hander Warner's innings came in the 10th over when he used his switch-hit right-hander stance to put Pakistan's star spinner Saeed Ajmal over the fence.
Ajmal held his nerve to take 2-19 from four overs while Yasir Arafat and Umar Gul also claimed two wickets.
Glenn Maxwell hit 27 but Australia's momentum stalled late in the innings as Cameron White, Dan Christian, George Bailey and Mike Hussey fell cheaply.
- AAP