CopyPosition.cs

using UnityEngine;
using System.Collections;

public class CopyPosition : MonoBehaviour {

    public Transform target;
    public bool copyX = false;
    public bool copyY = false;
    public bool copyZ = false;
    public float offsetX = 0f;
    public float offsetY = 0f;
    public float offsetZ = 0f;

    void Update () {
        Vector3 pos = transform.position;
        if (copyX)
            pos.x = target.position.x + offsetX;
        if (copyY)
            pos.y = target.position.y + offsetY;
        if (copyZ)
            pos.z = target.position.z + offsetZ;
        transform.position = pos;
    }
}