i think that slenderman, the rake, and a few others are just modern urban legends easily spread by the internet. kinda like the legends and "ghost stories" we all shared in our youth. not sure i would go as far as saying they are actual tulpas though. or have any physical abilities whatsoever, just more of active imaginations or the desire to see something strongly enough to be mis-led.
Dogmen i think are just another more modern term for werewolves, the legends have been around for centuries and this is just the modern versions. the moon has never played a part in the werewolf ability to transform and silver as well as iron and a few other elements or herbs has always been a part of different ways to ward off evil, so also not just related to the werewolf phenomena.
Bigfoot is similar, in that it can be related to the native american legends and stories, whether real or not i dont know, but i would still not think Tulpa before just a "mass hysteria" or "hypnosis" type answer. when ppl get in unfamiliar areas or situations they become hyper alert, if not controlled that can lead to fear taking over and causing everyday common sounds or sights to morph into your darkest fears or imagination.