开云体育

Johnny,

Hi, I wanted to transfer my adults only yahoo group to groups.io, but
I cannot find any info that adult groups are allowed on here.

It depends on the group's content:
/static/adult
(That link is in the TOS)

... if so how do I make my group available to adults only.

As Duane said, there is no mechanism to do that.

If you decide that your group fits within the content guidelines you might want to make the group's content members-only and restrict membership to people you approve.

Shal