You can just add a blank graphic and then go in an edit the graphic. In the edit window, you'll be able to add in a particle effect and make the graphic transparent. You'll just need to consider how large your collision shape will be in relation to the particle effects size.
I think i didn't explain well. I need to destroy my character by hitting with particles. i cannot find where to set collision shape for the graphics use as the particle.
The other potential way to do that would be with an enemy spawner. So you create a graphic that is the "particle" enemy and add a "spawner" component. This is what I am doing with Trixel Rocket for my Comet levels. You can add multiples(several enemy spawners) of them and spawn in different directions and at varied speeds. I also have a particle effect behind it as well. So it is 2 enemy spawners and a particle effect.
@jerry it is working 80% for my requirement. I have another small issue. I have added spawner to an enemy and linked that enemy to another object. I need to move that object while spawning enemies. I used linear velocity to move them. but the object is no moving. it is spawning enemies at the same place.
The spawner should take in whatever linear/angular velocity that you set for the main enemy object. The main spawner itself will not move but the "spawned" objects will move. Another way of doing it would be to attach/connect your spawner enemy to an object and move that object and that object would just be a decoration that is transparent.