"Trainers, Gengar will be available in Raid Battles THIS SATURDAY ONLY!"

Laughing out loud indeed

What do you expect, it's Niantic. :D

You know what the fail is?
Unless the gengar gets legacy move, it won't be too interesting. Yeah it gets a shiny but ... you can't get its pre-evolutions unless they add those as well on same day. It's just not worth the spotlight as it is. Also, tier 4 ... I doubt i'll find people for it.