Mewtwo, who was only available to fight by invite in Pokémon Go, is joining a Legendary Raid for the first time on Sept. 20.
The legendary Pokemon was previously only available in EX Raids, special raids that were only available to join if you were invited by random by Niantic. This will be a lot of trainers' first opportunity to catch the fierce psychic-type.
Mewtwo won't be in raids for long, however, only available until Oct. 23. Moltres, Zapdos, and Articuno will also be in raids from Sept. 13 to 20 and will have shiny variants available to capture.
That's not all. Niantic has also confirmed that previously region exclusive, Farfetch’d, Kangaskhan, Mr. Mime, and Tauros, will be available in 7km eggs for the entire month of September from today. It will be a great opportunity to snatch up some of the most elusive Pokémon from the original 151.
If you don't get one of these rare Pokémon by the end of September, then the only way to get them will be to travel to other parts of the globe. So if you want to save yourself on airline fees, not to mention customs lines, and airline food, then get out there and walk those eggs off until they hatch.