First I think they should have 2 types of bats (fruit bat and normal bat) you can tame the fruit bat by giving it any kind of fruit. You can tame the normal bat by giving it moths. You can get moths by having any kind of light source outside at night. They will fly around the light. Basically you just have to kill the moths and feed them to the bat. Bats would be useful for getting rid of bugs (bugs can bite) and when you sit your bats they will go and sleep on the nearest surface that it can get to.