From 12 p.m. until 1 p.m. in your local time zone, Origin Forme Giratinas will spawn at gyms, ripe for capture. We can likely expect it to function similarly to the last Legendary Lunch Hour, which means that eggs will have a 10 minute countdown timer until hatch and will be active for an hour after.
The announcement states that this is yet another test run. Legendary Lunch Hour isn’t guaranteed to stay after this, but Niantic wants to continue testing the concept. Niantic also added that the company is aware that not everyone can participate during this short time period, but reiterated that “these tests are the first step in creating more events focused on different play styles.”
To take down Giratina with ease, we’d recommend Rayquaza, Palkia, Dragonite, and Salamance, decked out with dragon-type moves. If you don’t have those on hand, Gengar and other ghost-types can help get the job done. Dark, ice, and fairy moves also will inflict double damage on Giratina. For more raiding information, you can check out our guide here.