Enemies In Different States

I want to do something similar to this:


It works but not very well. I do not know if it's the right way.
I have 4 Enemy objects and I have modified the "Collision Shape" of each of them differently.
I position them all equally and one below the other.
So that when the collision shot they disappear one by one.

Is there any different way to do it ???

 

My head is going to burst from so much thinking. I've been trying to optimize this effect for many hours ... Is there no one who can help me out? Thank you

 

Clever technique! This is how I would set it up, let me know if this helps

 

Hi Kelvin Ye,
It has truly gone spectacular! This is amazing!
Thank you very much for your help!