You can use groups but perhaps a slightly better feature you can use to achieve the same thing is collision layers and masks (see collision object documentation).
All collision objects can be be 'in' some subset of 32 collision layers and interact with collision objects in its collision mask for other collision layers.
All collision objects default to layer 1 (bit 0 of a collision mask/layer). This is why you had the on_enter trigger since likely you have a couple collision objects in your scene near to the player/target
In a more densely packed scene with more collidable objects in it, collision layers offer efficiency for the physics engine (read collision detection)
