I found the front calipers on my 2006 G6 GT quite bothersome compared to other vehicles I own. If I recall there was a large bolt holding the caliper in place, plus the two hex bolts. It was 1.5 years ago when I did the front brakes and the first vehicle I needed to use a breaker bar on to nudge that bolt loose. It was at least a 1/2" bolt. On my Ford Taurus and Dodge Durango there are no additional bolts on the caliper, just the two hex bolts holding the caliper on over the rotor.
'11 Ram SXT 4x4 quad cab - 5.7L V8; 128,200kms
'09 Malibu 2Lt 3.6L - 140,000kms purchased 1 March 2019
'06 Pontiac G6 GT - 3.5L V6; 162,000kms (rear ended 15 Feb 2019, and given totalled title by insurance)