After the fiasco that was Pokemon GO! Fest in Chicago, Niantic announced that Johto’s Lugia and the legendary birds were being unleashed upon the world and would be catchable in raid battles. Not long after, the company revealed that the legendary dogs (even though Raikou looks more like a saber-tooth) from the Johto region would soon be running around out there. As of August 31, that time has come, though in a different manner than their predecessors.
In Gold and Silver, and to a lesser extent in Crystal (wherein Suicune was part of the story), Johto’s doggies had trainers chasing them all over the countryside, putting them to sleep and whittling down their HP with False Swipe until they could start hurling ultra balls at them. The dogs’ elusiveness continues in Pokemon GO! to a slightly less (or maybe slightly more) degree of agony. To put it plainly, they’re all in different parts of the world. Yup, Suicune’s over there in Asia right now, while we have Raikou. Europe and Africa are now on the hunt for Entei. If you’re a GO! player and decide you need these pups, best hurry, ‘cuz they won’t stick around for long.
Each member of the Johto trio will hang around for a month before moving onto another region of the world, then wait another month before doing the same. What this means is that you have 30 days to catch the one in your corner of the planet, with a total of three months to snag them all. It’s unknown what their new locations will be once they switch around, but you can bet the Internet will have the answer to that when the time comes.
By the way Pokemon Company, Raikou is still waiting for his own feature films like Entei and Suicune got.