HI, my online exercises included this question:

1.A summons is usually served with what?

• the complaint

-What other document is usually served with a summons?

-a counterclaim, since it is equivalent to a complaint against the plaintiff

My question is:

Only plaintiffs do summons, right?

How can a plaintiff include a counterclaim? Only defendants can file a counterclaim, against a plaintiff?

Or... is the above counterclaim served instead of complaint? (is it because it's already tied to original complaint?)

Using the word usually... implies that it happens frequently, are counterclaims that common?