AI for Turret Game

Hey Everyone,

I made a turret game where you can turn and shoot, but i need to build multiple AIs as the enemies. There will be Battleships and airplanes, I need the planes to move different ways (Straight across but not completely going straight, meaning, showing some turbulant movement) And the ships just come straight across. The ships need to send the player to a new frame (death frame) and also shoot turrets at the player turret. I also need these enemies to randomly generate from a centralized point.

Does anyone know how to do this?
Can anyone help?