>>536221096
Shadow is extremotolerant, he has astrotolerance and radioresistance as well as barotolerance. He is polyextremotolerant. But I guess this could apply to Sonic as well.
>>536222071
Bullets bounce off of Shadow when he's got a field of energy surrounding him. There's no indication that if you just snuck up behind Shadow while he's chilling and shot him, it wouldn't injure him.