>>53875690 >>53875812PLA is like ORAS and USUM, being able to move eligible mons between games both ways. Therefore it's part of Gen 8.
LGPE are games that allow eligible mons out to Gen 8, but not back into itself. Therefore, it's not part of Gen 8. They makes more sense as their own separate thing than actually a part of Gen 7, since they has no compatibility with Gen 7.
Gen 2 is able to move eligible mons between itself and Gen 1 both ways. Therefore it's part of Gen 1, and the real Gen 2 was the friends we made along the way. 