Yes, this machine CAN use regular balls, Little League or otherwise. That said, ALL wheel-type pitching machine manufacturers recommend using dimple balls with their machines because, as we state in our Pitching Machine Balls Buying Guide, pitching machines pinch a ball as it goes through the machine. This eventually breaks the glue that holds the leather cover onto a ball, ultimately making the cover mushy and ripping it off the ball.
Unless you don't mind constantly buying new balls, dimpled balls are a better investment - they last forever and are the same size/weight as a real ball. If you DO elect to use regular balls, only use high quality leather balls with no protective coating on them.
One final thing ... dimple balls DO NOT dent bats. It is a myth that comes from public batting cages where they leave the balls out in the rain, making them waterlogged, heavier and harder than a real ball. Keep your dimple balls out of the rain and you'll be fine!