HI
There is 'aerial work' which covers things like banner towing, air taxi, inspection (of wires, pipelines navaids etc) and flying training. This is aerial work if done for reward, so a commercial licence would be needed. A lot of the 'young' do this to gain hours, but teaching well is not easy. I am now well retired, but I was taught to be instructor by the RAF - and I flew a biz jet before airlines!!
dbee