>>29842616In the first Ranger game you encounter both Groudon and Kyogre, its commented that they were both hurt, so its implied they came to that region to recover after their battle in Emerald.
The Ranger games are arguably canon, you get Manaphy from them as well.
Also Cynthia outright confirmed Platinum was canon in BW, so it would make sense the third games are the canon telling of region's events.