Hands can be placed at different places related to the body, strengthening different muscles in breast and arms.
They can be done on knees, feet, or with the feet raised, depending on strength.
Together in pairs. On holds the other in the classic wheelbarrow, both with strait back. The standing should hold the partners leg just above the knee, so that the partner only touches the ground with the hands. Now do push-ups where the partner follows by bending and straiten at the knees.
Together in pairs, one lies on the ground with the arms strait up into the air. The other put the fees in the other persons hands, and the arms at the partners feet. The top person now do push-ups.