Enemy Ai in Unity 3d for space shooter

I need someone to create more advance Enemy Ai for space shooter, ... I do have a basic one That needs some improving... which moves Enemies, and make them shot... But I would like a couple of variation with improved AI... to make enemy more intelligent ... In current script enemy (just like in any tower defence game) moves randomly shot randomly, and moves along z axes till it reaches end of the screen, where if not shoot by player get destroyed ... This is the basic Script that moves the ship; public class Enemy_EvasiveManeuver1 : MonoBehaviour { public Boundary boundary; public float tilt; public float dodge; public float smoothing; public Vector2 startWait; public Vector2 maneuverTime; public Vector2 maneuverWait; private float currentSpeed; private float targetManeuver; public float speedZ; void Start () { [login to view URL] = [login to view URL] * speedZ;// this moves forward currentSpeed = rigidbody.velocity.z; StartCoroutine(Evade()); } IEnumerator Evade ()// this randomly moves left and right and keeps the enemy within screen { yield return new WaitForSeconds ([login to view URL] (startWait.x, startWait.y)); while (true) { targetManeuver = [login to view URL] (1, dodge) * [login to view URL] (transform.position.x); yield return new WaitForSeconds ([login to view URL] (maneuverTime.x, maneuverTime.y)); targetManeuver = 0; yield return new WaitForSeconds ([login to view URL] (maneuverWait.x, maneuverWait.y)); } } void FixedUpdate () { float newManeuver = [login to view URL] (rigidbody.velocity.x, targetManeuver, smoothing * [login to view URL]); [login to view URL] = new Vector3 (newManeuver, 0.0f, currentSpeed); [login to view URL] = new Vector3 ( [login to view URL](rigidbody.position.x, [login to view URL], [login to view URL]), 0.0f, [login to view URL](rigidbody.position.z, [login to view URL], [login to view URL]) ); [login to view URL] = [login to view URL] (0, 0, rigidbody.velocity.x * -tilt); } } but I need few more a bit complex and intelligent attacking maneuvers.... First Maneuver 1- Once the enemy ship detects the player it does not pass him, instead hoover around and tries to kill him/shoot. combination of evade and attack movements , Enemy ship stays around and fight the player ( does not pass him) till one of them dies... 2nd Maneuver Same but, with variation ... if enemy would move in an arch like movement not strait diagonally... or anything you can suggest that is better 3rd Maneuver Enemy ship that is trying to avoid the player and pass and shoot into boundary( bottom of the screen) that we defend , this ship would also detect when player or players bullet are close(enter his collider- detection) and then teleport somewhere randomly on the screen . - Teleport skill needs to be cool-down ability, I also need to be able to fine tune the time how long it takes to teleport again. 4. Same idea but instead of teleporting enemy rise shields ... also cool-down ability... I will give more details if job granted ... No enough words to explain everything , but it should make sense to any good programmer..