BuddyPress.org

To hush the “No BuddyPress theme” nag you need to add a “buddypress” tag to your theme css header.

If you want to use BuddyPress with an existing WordPress theme you need to copy over the theme files. You’ll need to adjust the HTML to match you theme though.

This is never going to be the ideal way to do things though, the best experience with BuddyPress is always going to be building a site from scratch with BuddyPress in mind.