Guaranteed Shiny Mew Research is available in game as of today July 6th!
If you did the previous Shiny Mew research you will not be able to do this one.
The research is $5 USD in the Shop
With that it's pokemon go's 7th Anniversary.
Red party hat Squirtle evolutions debut.
You can find costume: Pika, Squirtle, Charmander and Bulbasaur in the wild as well as raids.
Edit: I'm gonna try to keep this PoGo forum up to date from now on . Hopefully it's helps out.