It would seem that more work was necessary on the EX Raid Battle system before Mewtwo was allowed to descend upon the greater Pokemon GO universe. While it was possible that Mewtwo would be released today, the three Legendary Dogs were unleashed instead. Mewtwo is still very much in play for the near future – just as soon as EX Raid Battles are fully sorted out.
Mewtwo isn’t a normal sort of Raid Boss. Unlike the lower tiers of Pokemon Raid Bosses, there’s absolutely no way a small group or single trainer can beat Mewtwo as a Raid Boss. We found that out through our friends in Japan – and the code for the game which dictates that Mewtwo isn’t one to be trifled with. As such, EX Raids are required. These raids are made specifically to bring large amounts of people into a single Raid Battle so that they might have a chance to beat the Pokemon Raid Boss at hand – in this case, Mewtwo.
EX Raid Battle (formerly Exclusive Raid Battle)
What was previously referred to as “Exclusive Raid Battles” will now be called “EX Raid Battles”. These battles are NOT yet in the game (as of the posting of this article) but they will be soon. The EX Raid Battle system will be in field-testing very soon, and the release regions for this system will be appearing soon.
Niantic will be releasing EX Raid Passes “soon” to Pokemon GO users around the world, and the first EX Raid will take place as early as September 6th. This is straight from a Niantic rep, who also says that the roll-out to different sorts of users will be made based on several factors. Periodic adjustments to EX Raid (test) eligibility requirements will be made, along with frequency, times, locations, and durations.