>>46707537Not that anon but not every game. I know that at the very least though from FRLG/Emerald onwards it's been happening on account of the Battle Tower/Facilities.
FRLG has Johto Mon in the Tower and the Battle Frontier has many Johto Pokemon and even Legendaries.
The Battle Subway has NPCs that can use any combination of non-banned fully evolved Mon from Gen 1 to Gen 5 and of course, the parties used in the Battle Maison and Tree are reflective of the trainers rather than the region so they were never tied to a particular dex.
