Does the mantis doll count as a lethal weapon? I ask this because, when you use it on screaming mantis, you still get her statue. So if you use this weapon on the other B&B's, will you get their statues as well?

I think Screaming Mantis is the exception because the mantis doll is the only way you can defeat her.

Other B&B's can be defeated using other non-lethal weapons so I don't think the mantis doll will work on them if you want to get the statues.

The Mantis Doll counts as a non-lethal weapon against Screaming Mantis, since it is the only way you can take her Beast form down.