Learn Hardcore Norwegian: Vi møtes ved kirken.

Here møtes means meet each other or are meeting. So Vi møtes is the natural way to say that two or more people are meeting one another.

Why is it møtes and not møter?

Møter is the ordinary present-tense form of å møte, and it often means meet, see, or encounter someone or something.

But møtes is commonly used when the meeting is mutual. In other words, everyone is meeting everyone else.

Vi møter noen ved kirken = We meet someone at the church
Vi møtes ved kirken = We meet each other at the church

In this sentence, møtes is the most natural choice.

Do I need hverandre in this sentence?

No. You do not need hverandre here.

That is because møtes already gives the idea of each other. So:

Vi møtes ved kirken is natural
Vi møter hverandre ved kirken is possible, but less natural in this situation

So the short answer is: møtes already does that job.

Why is the preposition ved used?