Was gonna say the thing about Dream World Shinies but Sater beat me to it haha.
On Muk, I actually decided to Google the dude and I found him on Tumblr. He's a GTS/WonderTrade person.
Here is the post where he shows his Muk along with others. Unfortunately, as stated
on his page about hacks, he admits they are all
hacks. Need to get this guy's OT/ID on the Hack Report List.
Sceptile I'm not sure. Shiny and HP Fire is sketch, but not impossible. I'd
set it to the side to be safe.
Gourgeist I also Googled the OT and apparently the dude is a
Twitch streamer and is across, like, all of social media but isn't super popular. He did some videos on his YouTube about MMing and I haven't found evidence of foul play otherwise, so I'm gonna say it's
probably okay. Might follow him, find when he's streaming and straight up ask for the sake of the trading community.
Rapidash I ALSO Googled and got a bunch of posts across the GameFAQs Pokemon trading sections. The user had the same OT and had a Ponyta in his list of Shinies. I'm guessing it got traded around and someone trained it. The guy isn't banned and its not impossible to have (and his list of Shinies was only a handful of them), so I'll say it's
okay.
Hope that helps! c:
