Can anyone help with enemy pathing within a 2D shooter?

Currently trying to do some form of pattern for enemies to move in for the 2D shooter im making, the scene scrolls down so the ship is facing up. I want to be able to create a script that will be reusable for e.g. script 1 would have a certain pattern to its movement so if i just dropped it onto a enemy ship or even perhaps call a method that would do a certain pattern. the code needs to be as reusable as possible so if sometime in the future i wanted to make a level editor for e.g. i could maybe drop the patterns onto the scene through the editor or just have the scripts create the pathing using on screen coordinates if thats possible? i'm a total amateur at game Dev and unity so any help would be massively appreciated :)