>>56226919>he updates his computer>mfwAnyways, that question is an all-hands-on-deck situation. Legendaries are so rare in their native environments that most people don't even know they exist, let alone what they look like (ie, Kanto birds go unmentioned by any NPC, Groudon and Kyogre are just referred to as "red one/blue one" while dueling in Sootopolis, Dialga/Palkia statue is a weird mismatch, etc.). Characters that even recognize Legendaries exist (Eusine & Morty, Cynthie, the Plasma Sages, the Lumiose Gazette chief) are already earmarked as truly remarkable individuals and they haven't even caught a Legendary. For the layman, that Entei (you) caught is just a really cool Fire-Type they haven't seen before.
Having a Legendary show up where it doesn't belong is so utterly out-of-context for all but the most elite 1%ers that any documentation or confirmation of their presence would kick off a One Piece-style scramble as every Trainer with any sense of ambition sets off to try and catch it for themselves.
That's just the human element. An Apex Species entering the territory of another Apex Species is going to cause a massive shakeup in the ecosystem if the native top dog isn't able to defend its claim. See also: Deoxys and Fug, the Kanto birds and Lugia. Many of these species are capable of reshaping the entire biosphere with their abilities, so you're going to see major changes in what lesser Pokemon are available as well as displaced species are replaced by opportunists seeking to fill the newly-created vacuum.
All together, when Legendaries are on the move, the entire planet moves with them.
